MAPI vs. SMTP: Top 4 Differences You Should Know - Spiceworks (2024)

  • Messaging Application Programming Interface (MAPI) is defined as a proprietary protocol by Microsoft that gives users access to Exchange Server functions such as email and folders.
  • MAPI enables the transfer of messages from cloud storage to local storage, among other functions.
  • Conversely, Simple Mail Transfer Protocol (SMTP) is defined as a protocol for communication among computers using email addresses.
  • SMTP defines communication rules among servers and supports various communication modes, such as one message to multiple clients and audio and video transfer.
  • This article covers the top differences between the two email protocols.

Table of Contents

  • MAPI and SMTP: An Overview
  • What Is MAPI?
  • What Is SMTP?
  • MAPI vs. SMTP: Top 4 Comparisons

MAPI and SMTP: An Overview

Messaging Application Programming Interface (MAPI) is a proprietary protocol by Microsoft that gives users access to Exchange Server functions such as email and folders like inbox and outbox. MAPI enables the transfer of messages from cloud storage to local storage, among other functions.

MAPI vs. SMTP: Top 4 Differences You Should Know - Spiceworks (1)

MAPI vs. SMTP Architecture

Sources: MicrosoftOpens a new window and GeeksforGeeksOpens a new window

Conversely, Simple Mail Transfer Protocol (SMTP) is a protocol for communication among computers using email addresses. SMTP defines communication rules among servers and supports various communication modes, such as one message to multiple clients and audio and video transfer.

Before diving into their differences, let’s learn a little more about MAPI and SMTP.

What Is MAPI?

Messaging Application Programming Interface (MAPI) consists of common application programming interfaces (APIs) combined with a dynamic-link library (DLL) component. The APIs are used to build and access various messaging systems and applications, thus supporting the creation of a consistent environment for users and developers.

The MAPI subsystem is contained within the DLL. It is useful for managing interactions between messaging applications on the front end and messaging systems on the back end. It is also responsible for providing a common user interface for recurring tasks and supporting a central “clearing house” that unifies several messaging systems and allows clients to ignore the differences among them.

See More: What Is Remote Desktop Protocol (RDP)? Meaning, Working, Benefits, and Challenges

What Is SMTP?

Simple Mail Transfer Protocol (SMTP) is a protocol that enables the transfer of emails from one account to another over the Internet. Like IMAP, POP, and other email protocols, SMTP provides a set of rules that email accounts and clients follow to streamline the exchange of information.

SMTP is the only protocol dedicated to sending emails. Many popular email clients, such as Microsoft Outlook, Google Gmail, Yahoo Mail, and Apple Mail, use SMTP to “push” messages from sender to receiver.

An SMTP server is an application that provides email sending, receiving, and relaying services to clients within a network. It is comparable to a real-life post office, where a letter goes from the sender to their local post office, then to the receiver’s local post office, and finally to the receiver. However, unlike a physical letter that can take days to reach its destination, SMTP transfers emails within a few minutes at most.

Finally, an SMTP port is the communication endpoint that takes care of data transfer for email over SMTP as it is transmitted from one server to another through a network.

See More: Switch vs. Router: Understanding 15 Key Comparisons

MAPI vs. SMTP: Top 4 Comparisons

MAPI and SMTP are both popular email protocols. MAPI is a proprietary Microsoft protocol used primarily for email clients running on Windows, such as Outlook. At the same time, SMTP is an open standard protocol used by most email servers and clients.

While both protocols can be used for sending and receiving emails, there are some key differences between the two in terms of functionality, architecture, and applications. Let’s learn more.

1. Functionality

An open and comprehensive programming interface along with compatibility with industry standards are two key functionalities of MAPI. These features give developers access to a consistent methodology for seamlessly working with different messaging systems.

The MAPI open programming interface provides generic services that can be topped with customizations as users require. It has the functionality to fulfill the diverse requirements of messaging platforms, such as word processing, document sharing, workgroup creation, and diverse data storage. Essentially, MAPI provides comprehensive data storage and exchange functionalities and other unique features of its messaging system that can benefit application users.

MAPI also separates the programming interfaces for front-end messaging clients and back-end service providers. This gives single applications the ability to use several messaging systems and multiple applications to leverage a single service provider.

All MAPI components are compatible with a common user interface based on Microsoft Windows. Several systems are available for selection depending on user needs. Users can also work consistently with every selected system, which means MAPI functionality allows for absolute independence from specific messaging systems.

For instance, a messaging client can use MAPI to receive messages from voicemail, RSS feed, and fax. Messages will be received in a single “universal inbox” on arrival. An application handling all these systems reduces the costs associated with development, system administration, and user training.

Separating the client and provider interfaces removes programming dependencies placed on the messaging system by the application and vice versa. Client application devs and service providers can create code for a specific set of MAPI functionalities rather than several distinct messaging-specific or application-specific features. Developers can focus on their components (either service-side or client-side), and MAPI brings them all together, thus minimizing development costs and time.

The MAPI programming interface is feature-rich and aimed at streamlining workgroup applications, which are applications that communicate with various messaging systems like DEC All-In-1, voicemail, fax, and even public communications services like CompuServe, MCI MAIL, and AT&T Easylink Services. Service providers can be made available for all these systems over the MAPI interface.

Finally, MAPI supports cross-platform functionality for industry standards such as X.400 and SMTP. MAPI applications can run on older Windows versions, including 7, Vista, Server 2008, Server 2003, and Windows XP.

SMTP functionality covers the sending process and the specific commands and rules that enable message transmission.

SMTP functionality begins with establishing an SMTP server, which allows email clients to connect with it for communication. Emails sent from users are transmitted from the email client over an SMTP connection to the server. This SMTP connection is built over the Transmission Control Protocol (TCP).

The SMTP client then uses commands to share instructions with the server and transfer data, such as the email addresses of the sender and the recipient and the contents of the email.

In the next step, the MTA (Message Transfer Agent or Mail Transfer Agent) checks whether both email addresses are from one email domain, such as If the domains are common, the email is transmitted right away. If not, Domain Name System (DNS) is used by the server to identify the receiving domain, after which the email is sent to the correct server.

Basic SMTP commands — codes that power SMTP functionality such as email transmission between servers — are as follows:

1) HELO or EHLO (Hello): This command kicks off the email-sending process. It is used by the email client to identify itself with the SMTP server. The command is then sent back by the server, along with its domain name and IP address.

2) MAIL FROM: Once identification is completed, this command is used to specify the email sender. This code transmits the email address and notifies the SMTP server that a new transaction is being initiated. The server then resets everything in preparation for accepting the email address. The server will reply with a “250 OK” code if the email address is accepted successfully.

3) RCPT TO (Recipient To): This command identifies the email recipient once the 250 OK reply code is received. The SMTP server again responds with 250 OK, after which another RCPT TO command with a different receiver’s email address can be sent. This process repeats several times, depending on the number of email recipients.

4) DATA: This command is used to trigger the data transfer process between the client and the server. Once this command is executed, all email contents are transferred to the SMTP server, which replies using a “345” code. A single dot is sent in a line by itself after the message contents are transmitted to the server to notify it of the end of the message. If the server successfully accepts the message and prepares it for delivery, it sends another “250 OK” code to the sender client.

5) QUIT: Once the email is sent, the client sends this command to the SMTP server, closing the connection. If successful, the server replies with a “221” code.

6) RSET (Reset): This command is sent when the email transaction has to be stopped. While this command does not close the connection, it resets everything and flushes all previous data about the email and its sender and recipients. This command is used in case of an error, such as the entry of incorrect recipient information, post which the process must be restarted.

Finally, an SMTP Relay is defined as the process of transmitting emails between SMTP servers. It consists of the Mail Delivery Agent (MDA) and the MTA. It usually occurs when the sender and receiver have email addresses from different domains. SMTP Relay services increase email deliverability rates, helping users ensure outgoing messages reach the recipient’s inbox.

While “SMTP Host” refers to the server the email is sent over, the SMTP Relay is the process executed on that server.

2. Architecture

MAPI features a modular architecture.

Because it is a client of the MAPI subsystem, the MAPI application is referred to as a client application.

The MAPI subsystem architecture consists of programming interfaces and a common user interface. The latter is a set of dialog boxes that helps establish a consistent look for client applications and a consistent user workflow.

The MAPI programming interface is leveraged by the MAPI subsystem, developers on the service provider side, and client-side software developers. It is the main object-based programming interface and is similar to the OLE Component Object Model.

The MAPI programming interface is used by messaging-based client applications written in C or C++ and the MAPI subsystem. This interface enables client software developers to make MAPI calls directly.

Messaging functionality can be implemented with either one MAPI client interface or a combination of interfaces. In the latter case, a single application can make calls to functions or methods belonging to any of the interfaces.

The User Agent (UA) and Mail Transfer Agent (MTA) are two key components of SMTP architecture.

On the sender side, the UA creates the message and transfers it to the MTA. The MTA is then responsible for transferring the email content to the receiver MTA across the network.

Within the SMTP architecture, the client MTA is responsible for sending the email, while the server MTA is the component that receives emails.

The MTA uses TCP/IP to exchange messages between the sender and receiver.

It is responsible for queuing the pool of messages — in cases where the receiver is temporarily unavailable, the MTA schedules the messages for repeat delivery. The system administrator can configure the local MTA, removing the need for senders to manage it.

Once the MTA transmits the emails to the user’s local mailboxes, the UA can download them as required.

3. Applications

MAPI over HTTP in Exchange Server is a key application of MAPI.

MAPI over HTTP is a transport protocol that enhances the stability and reliability of the connections between Outlook and Exchange. This is achieved by moving the transport layer to the HTTP model, an established industry standard.

This protocol enables higher visibility of transport errors and improved recoverability. An added feature is the support for an explicit pause-and-resume capability that allows supported clients to switch networks or resume from hibernation without foregoing the existing server context.

If users choose to implement MAPI over HTTP, they do not have to give up on using other protocols for Outlook to access Exchange. Outlook clients lacking MAPI over HTTP capability can still leverage Outlook Anywhere (RPC over HTTP) to connect with Exchange over a MAPI-enabled Client Access server.

Exchange 2016 and Exchange 2019 allow users to apply MAPI over HTTP either across the entire organization or to individual mailboxes.

MAPI over HTTP offers several benefits to supporting clients. For instance, it drives innovation in authentication by relying on an HTTP-based protocol.

Additionally, it supports quicker reconnection times in case of a communications break, as only TCP connections, not Remote Procedure Call (RPC) connections, would need to be rebuilt. Communication breaks may occur due to device hibernation or switching from wired to cellular or wireless networks.

Finally, MAPI over HTTP offers a session context that is connection independent. The session context is maintained by the server for a configurable period, even in cases where the user changes the network.

As a more universal protocol, SMTP has several applications, including email marketing.

SMTP removes sending volume limits for users, which is especially helpful as many internet service providers (ISPs), web hosts, and email service providers limit the number of emails a user can send in a specific period. A dedicated SMTP allows users to send as many emails as required without limits.

Additionally, users can comprehensively monitor email delivery. Whether the email is delivered or not, SMTP allows users to receive helpful delivery information. For instance, users can monitor whether their messages were transmitted to the right recipient and analyze any arising error codes.

SMTP also allows users to maintain the privacy of their email lists. Using a private SMTP means email list data is not shared with any third party. This helps maintain the privacy of company and customer data.

However, it is worth noting that SMTP applications come with their own share of investment in terms of money, time, and effort. Operating an SMTP server needs a lot of resources, and users must constantly monitor and manage all operations. This can translate to having dedicated personnel for server setup and management. The costs of SMTP applications should be weighed against their benefits.

Unlike public cloud storage, SMTP servers operate locally. This has numerous advantages for specific use cases. However, it can also translate to vulnerability to internet issues or power outages. These operational challenges can be overcome by using backup servers and failsafe protections.

SMTP applications can be streamlined by adopting a third-party provider. Such service providers can configure SMTP to minimize email security and deliverability issues, even when contacting a large pool of recipients.

4. Advantages

The main advantage that MAPI holds over SMTP is its capability to send and receive emails since it can access folders like inbox and outbox. Conversely, SMTP is exclusively useful for sending emails, and users must opt for another protocol like IMAP or POP to receive emails.

Another benefit of MAPI is its capability to automatically retain a copy of sent emails, as all emails are routed through the sender’s outbox. This feature does not come in-built with SMTP, and users must either include themselves in the “BCC” field of their emails or program their servers specifically to retain copies of their sent emails.

Basically, for users of Outlook and Microsoft Exchange, MAPI is the more advantageous option as it was specifically developed to serve as a bridge between these two solutions.

Additionally, using MAPI over HTTP increases the efficiency of interactions with Exchange mailboxes as against Remote Procedure Calls (RPC).

Even though both MAPI and RPC are encapsulated within HTTP architecturally, users can reestablish connections with Exchange servers faster after network disruption when using MAPI over HTTP rather than Outlook Anywhere.

MAPI over HTTP also features more robust security when switching networks, such as from the enterprise network to a personal cellular network. In such cases, the server retains the active session as it was before the network was switched.

Personal networks are also more secure and reliable with MAPI over HTTP, especially for Outlook clients connecting to Exchange Server 2019.

Another key advantage of switching Outlook to MAPI over HTTP is an improved user experience and the faster delivery of emails across all types of connections. Swifter connection times to Exchange are a major reason for this advantage.

Finally, MAPI over HTTP boosts the reliability and stability of the connections between Outlook and Exchange by shifting the transport layer to the HTTP model. This makes it easier to spot transport errors, thereby enhancing recoverability.

A key advantage of SMTP over MAPI is its widespread support.

MAPI was introduced as a Microsoft protocol for use with Outlook. As Outlook and Microsoft’s Exchange server gained popularity, more email clients adopted the protocol. However, SMTP is more popular as it has been around virtually since email was invented. Every major email client today is capable of supporting SMTP use. In fact, it is the default protocol in many cases.

Additionally, SMTP is client-agnostic, allowing users to switch clients without affecting functionality. This is not the case with MAPI, where users must make changes to the configuration if clients are switched, as the server would not automatically be able to detect the client change.

SMTP is especially popular among users of non-Microsoft email clients, such as Mozilla Thunderbird, wishing to connect to free email servers such as Google Gmail.

In many cases, users only have to enter their credentials, and they’re done.

Apart from this, SMTP offers back-end access to messages that explain error codes in case an email fails to be delivered.

Users can also set up SMTP servers to receive email statistics. This feature allows for generating statistical reports for click and open rates and other metrics.

Finally, SMTP systems can be synchronized at the server level to carry out bulk actions. For instance, a setup consisting of a hundred computers that all need synchronization with an SMTP server does not need each computer configured individually. Rather, users can execute synchronization at the server level, allowing them to manage all email accounts.

See More: What Is IPv6 (Internet Protocol Version 6)? Definition, Features, and Uses


SMTP is used exclusively for sending emails, while MAPI allows sending and receiving emails and access to email folders such as the inbox and outbox.

MAPI was originally developed by Microsoft for use with Outlook and Exchange Server but has since been adopted by other email clients as well. However, it does not enjoy the same popularity as SMTP, which all major email clients support.

The choice between MAPI and SMTP is dictated by the user’s configuration and use case. For large-scale Outlook/Exchange deployments, it makes more sense to use MAPI, and for other email clients, such as Mozilla Thunderbird, SMTP is a good option.

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MAPI vs. SMTP: Top 4 Differences You Should Know - Spiceworks (2024)


What is the difference between SMTP and MAPI? ›

SMTP is used exclusively for sending emails, while MAPI allows sending and receiving emails and access to email folders such as the inbox and outbox. MAPI was originally developed by Microsoft for use with Outlook and Exchange Server but has since been adopted by other email clients as well.

What is the difference between how the IMAP Internet message across protocol and SMTP simple mail transfer protocol are used? ›

IMAP is used to retrieve messages, and SMTP is for sending data. IMAP works between the server and client for communication, and SMTP works between servers to transfer information. IMAP allows users to organize emails onto the server, while SMTP allows organizing emails on client storage.

What is the difference between MAPI and IMAP4? ›

While IMAP transmits all the contents of your messages in plain text which makes it easy to intercept, it can use SSL encryption to encrypt messages. MAPI is more secure than IMAP because it allows you to use 128-bit RPC encryption in the Outlook user profile. MAPI also provides a live connection to the server.

What is the MAPI protocol? ›

MAPI is a client protocol that lets users access their mailbox by using Outlook or other MAPI email clients. By default, MAPI access to a user mailbox is enabled. Disabling MAPI access to a mailbox prevents the user from using Outlook to access their mailbox in Exchange mode.

What port does SMTP use for MAPI? ›

SMTP uses TCP port 25 or 2525 and sometimes you can have problems sending your messages in case your ISP has closed port 25 (How to check if port 25 is open?). To determine the SMTP server for a given domain name, the MX (Mail eXchange) DNS record is used. SMTP is the most common internet standard for sending email.

What is the difference between SMTP and protocol? ›

SMTP (“Simple Mail Transfer Protocol”) is used for sending and delivering from a client to a server via port 25: it's the outgoing server. On the contrary, POP (“Post Office Protocol”) allows the user to pick up the message and download it into his own inbox: it's the incoming server.

What are the 4 protocols used in email? ›

The common protocols for email delivery are Post Office Protocol (POP), Internet Message Access Protocol (IMAP), and Simple Mail Transfer Protocol (SMTP). Each of these protocols has a standard methodology to deal with the emails and also has defined functions.

What are the differences between the three email protocols IMAP4 POP3 and SMTP )? ›

We have seen that the three main TCP/IP protocols for email delivery are SMTP, POP3, and IMAP. While SMTP is for sending emails, IMAP and POP3 are for receiving them. Basically, you can choose between IMAP and POP3 based on your needs. Both have their advantages; however, usually, IMAP suits most people.

What is the main difference between the two protocols for receiving email? ›

The main difference between POP3 and IMAP is that POP3 downloads emails from the server and stores them locally, while IMAP syncs emails across multiple devices and keeps them stored on the server.

What is the difference between Post Office Protocol and IMAP? ›

POP3 only allows a single device at a time to access the emails. IMAP allows multiple devices at a time to access and read the available mails. A user cannot update or create emails on the mail server by using the POP3 protocol. You can use the IMAP protocol for updating or creating emails.

What is the difference between MAPI over HTTP and Outlook Anywhere? ›

MAPI over HTTP is the default transport protocol to connect clients to Microsoft Exchange and Exchange Online. The Messaging Application Programming Interface (MAPI) over Hypertext Transfer Protocol (HTTP) supersedes the Remote Procedure Call (RPC) over HTTP protocol, which is also known as Outlook Anywhere.

What is the difference between Internet Message Access Protocol IMAP and Internet Message Access Protocol IMAP over SSL? ›

An IMAP server listens on port number 143, while IMAP over Secure Sockets Layer (SSL)/Transport Layer Security is assigned port number 993.

How to check MAPI over HTTP? ›

You can test the end-to-end MAPI over HTTP connection by using the Test-OutlookConnectivity cmdlet.
Logs for MAPI over HTTP activity are at the following locations:
  1. %ExchangeInstallPath%Logging\MAPI Address Book Service\
  2. %ExchangeInstallPath%Logging\MAPI Client Access\
  3. %ExchangeInstallPath%Logging\HttpProxy\Mapi\
Feb 21, 2023

Is MAPI over HTTP secure? ›

The first referred to a MAPI instead of TLS. This is Microsoft's proprietary messaging API. Whenever you see MAPI these days that's a secure protocol that goes over HTTPS, over TLS. In the old days it didn't necessarily use security, but nowadays, and especially with Outlook online, it's secure.

Does MAPI over HTTP support modern authentication? ›

MAPI over HTTP supports modern authentication, which means its initial connection to Exchange Online uses modern authentication, allowing for Outlook profile reconfiguration. MAPI over HTTP can be enabled either globally or at a per-mailbox level.

What is the default MAPI port? ›

MAPI port number. The default value is 7830. Specify the MAPI Exchange port for optimization. Typically, you do not need to modify the default value, 7830.

What TCP IP layer is SMTP? ›

SMTP is part of the application layer of the TCP/IP protocol.

Does SMTP use TCP or UDP? ›

There are three common protocols used to deliver email over the Internet: the Simple Mail Transfer Protocol (SMTP), the Post Office Protocol (POP), and the Internet Message Access Protocol (IMAP). All three use TCP, and the last two are used for accessing electronic mailboxes.

What is SMTP protocol in simple words? ›

SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving email. SMTP is used most commonly by email clients, including Gmail, Outlook, Apple Mail and Yahoo Mail. SMTP can send and receive email, but email clients typically use a program with SMTP for sending email.

Is SMTP push or pull? ›

The main difference between these protocols is that SMTP is the only protocol for sending or “pushing” email from one unknown mail server to another. POP and IMAP are protocols for receiving or “pulling” mail for the recipient from their own mail server.

Can SMTP be used as a mail access protocol? ›

SMTP is the most widely used protocol for mail transfer between servers.

What is an advantage for SMTP? ›

Advantages of Using an SMTP Server

It supports bulk mailing. Low cost and extended area coverage. Provide options for tracking emails. Reliable and quick email delivery.

What are the four layers of the TCP IP model? ›

4 The TCP/IP Protocol Stack is made up of four primary layers: the Application, Transport, Network, and Link layers (Diagram 1).

How does SSL work with SMTP? ›

In contrast, SMTPS utilizes either TLS or SSL to secure email communications using asymmetric cryptography. The main takeaway is that just an SMTP setup is susceptible to attacks, while SMTPS secures the connection by leveraging TLS for email.

What protocol is used by Outlook to connect to Exchange? ›

The Outlook client connects to this port and is assigned random TCP server ports to communicate with the Exchange server using the MAPI protocol. These MAPI connections are used to send and receive emails, calendaring, address lookup, and more.

What is the difference between SMTP and SNMP? ›

Simple Mail Transfer Protocol - SMTP is a standard for email transmission used for monitoring and alerting you to the health of devices in your network. Simple Network Management Protocol - SNMP is an industry standard protocol for monitoring devices on IP networks.

Which protocol is best for receiving email? ›

POP3 is the standard for receiving emails. Its flow is also simple: After you send a transactional email, SMTP does the sending part. POP3 reaches the mail server, grabs the message and forwards it to a recipient inbox.

Is SMTP used for sending emails between two or more servers? ›

SMTP is a protocol used to transfer e-mail messages and attachments. SMTP is used to transmit e-mail between e-mail servers and from e-mail clients (such as Microsoft Outlook) to e-mail servers (such as Microsoft Exchange).

Is IMAP an email protocol or a server script protocol? ›

IMAP is defined as an email protocol that allows access to email from any device. IMAP does not download or store the email content onto the device; rather, users read their messages over the email service.

What is the difference between simple mail transfer protocol and Post Office Protocol? ›

SMTP and POP3 are message protocols which are required for sending and receiving the messages between the mail servers.
Difference between SMTP and POP3.
TypeSMTP acts as a MTA (Message Transfer Agent) for sending the message to the receiver.POP3 is a MAA (Message Access Agent) for accessing the messages from mail box.
4 more rows
Aug 4, 2022

What is the difference between SMTP IMAP and POP3 servers in email commands? ›

Incoming vs.

As this is the protocol handling the email sending from an email account, it is labeled as the outgoing protocol. In short, thanks to IMAP and POP3, you are able to receive emails, and SMTP allows you to send messages.

How do I use MAPI in Outlook? ›

Use the new Exchange admin center to enable or disable MAPI

Under Mailbox settings > Email apps, click the Manage email apps settings link. In the Manage settings for email apps display pane, do one of the following. To disable MAPI, for the Outlook desktop (MAPI) option, when the button is Enabled, set to Disabled.

What are the differences between TLS and SSL? ›

A primary difference between SSL and TLS is message authentication. SSL uses message authentication codes (MACs) to ensure messages are not tampered with during transmission. TLS does not use MACs for protection but instead relies on other means, such as encryption, to prevent tampering.

Which protocol is used to secure web traffic? ›

Hypertext transfer protocol secure (HTTPS) is the secure version of HTTP, which is the primary protocol used to send data between a web browser and a website. HTTPS is encrypted in order to increase security of data transfer.

What replaced MAPI? ›

The MAPI/CDO library has been replaced by Exchange Web Services (EWS), Exchange ActiveSync (EAS), and Representational State Transfer (REST)* APIs.

Is MAPI used by Outlook? ›

Extended MAPI is the main e-mail data access method used by Outlook, to interface to Microsoft Exchange, via MAPI service providers shipped with Outlook.

How do I block MAPI over HTTP? ›

Steps to disable MAPI over HTTP (Manual Option)

Open the Registry Editor, by clicking on Start and typing "Regedit.exe". Right-click "MapiHttpDisabled" and the click Modify. Change the Value to 1 and then click OK. Close the Registry Editor.

What is the difference between MAPI and SMTP? ›

SMTP is used exclusively for sending emails, while MAPI allows sending and receiving emails and access to email folders such as the inbox and outbox. MAPI was originally developed by Microsoft for use with Outlook and Exchange Server but has since been adopted by other email clients as well.

Is MAPI encrypted? ›

The three main kinds of transport encryption are: Encrypted Messaging API (MAPI), Secure Sockets Layer (SSL) or Transport Layer Security (TLS), and IPsec.

Does Exchange still use MAPI? ›

In Exchange 2016 and Exchange 2019, MAPI over HTTP can be applied across your entire organization, or at the individual mailbox level.

Is MAPI a legacy authentication? ›

The legacy authentication protocols such as SMTP, POP, MAPI, and IMAP can't enforce 2FA/MFA, making them targeted endpoints for attacks.

Is SMTP being deprecated? ›

SMTP AUTH will still be available when Basic authentication is permanently disabled on October 1, 2022.

Is MAPI a legacy protocol? ›

This is because legacy authentication protocols like POP, SMTP, IMAP, and MAPI can't enforce MFA, making them preferred entry points for adversaries attacking your organization... ...

What does MAPI mean email? ›

The Messaging Application Programming Interface (MAPI) is a programming interface specification that enables an application to send and receive mail over a Microsoft Mail messaging system. It was designed to separate the mail engine from the mail client.

How do I know if my Outlook is MAPI? ›

On the mailbox properties page, click Mailbox Features. Under Email Connectivity, verify whether MAPI is enabled or disabled.

What does SMTP mean in Outlook? ›

SMTP stands for Simple Mail Transfer Protocol and it's the industry standard protocol for email sending. With SMTP you are sending, relaying, or forwarding messages from a mail client (like Microsoft Outlook) to a receiving email server.

Is Gmail a POP or MAPI? ›

Gmail, Google's internet-based email service, runs on the Internet Message Access Protocol (IMAP) system. It also offers Post Office Protocol (POP) mail server access.

Does Gmail use MAPI? ›

MAPI for Gmail® is compatible with any file extension or software. MAPI for Gmail® is compatible with any software and you can use it from any device where you install it.

How do I configure MAPI in Outlook? ›

Creating the MAPI Profile

If you have Outlook installed on the web server, you can add MAPI profiles using the Mail Settings in the Control Panel. Open the Mail Setup dialog box by selecting Control Panel > Mail. Select the Show Profiles button. Add the MAPI profile.

What clients use MAPI over HTTP? ›

MAPI over HTTP is the default transport protocol to connect clients to Microsoft Exchange and Exchange Online.

What email programs are MAPI compatible? ›

MAPI is an acronym for Message Application Program Interface. MAPI-compliant means that your email application complies with Microsoft Windows standards for connecting to other programs, email, and phone systems. Examples of MAPI-compliant email applications are Netscape Messenger, Outlook, Outlook Express, and Eudora.

How do I know if MAPI over HTTP is enabled? ›

You can test the end-to-end MAPI over HTTP connection by using the Test-OutlookConnectivity cmdlet.
Logs for MAPI over HTTP activity are at the following locations:
  1. %ExchangeInstallPath%Logging\MAPI Address Book Service\
  2. %ExchangeInstallPath%Logging\MAPI Client Access\
  3. %ExchangeInstallPath%Logging\HttpProxy\Mapi\
Feb 21, 2023

Do all emails use SMTP? ›

SMTP is used most commonly by email clients, including Gmail, Outlook, Apple Mail and Yahoo Mail. SMTP can send and receive email, but email clients typically use a program with SMTP for sending email.

Why use SMTP for email? ›

SMTP helps prevent spam by verifying the sender's account before delivering an email. By preventing spam emails, SMTP also protects your IP reputation. SMTP increases delivery rate by restricting spam and protecting IP reputation. SMTP notifies senders if an email address is invalid or incorrect.

What is SMTP standard for? ›

The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages.


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