MAPI vs SMTP: Difference and Comparison

When it comes to email handling protocols, there is a variety to choose from. SMTP and MAPI are two of these protocols.

Microsoft designs MAPI, and SMTP is designed by RFC 821. Both are wonderful choices; however, their particular applications differ. 

Key Takeaways

  1. MAPI (Messaging Application Programming Interface) is a Microsoft protocol that enables email and other messaging services in Microsoft Outlook and Exchange.
  2. SMTP (Simple Mail Transfer Protocol) is a widely used internet standard for email transmission across IP networks.
  3. MAPI provides more advanced features, such as calendar and contact synchronization, while SMTP is a simpler protocol focused on email delivery.


MAPI is a proprietary protocol to facilitate email communication between Microsoft Outlook and Microsoft Exchange Server. SMTP is a text-based protocol used to send and receive email messages over the internet and is the standard protocol used by most email clients and servers.


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MAPI is a proprietary protocol developed by Microsoft that allows Microsoft Outlook email clients to access exchange server operations such as email and other folders.

It enables us to transfer a message from cloud storage to local storage. We can use this tool to back up essential emails. This is an alternative to the IMAP or POP protocols for email retrieval. 

SMTP is a protocol for transferring communication information via email addresses from one computer to another. The communication rules between the servers are built up using SMTP.

It supports a variety of communication methods, including sending a single message to several customers, transmitting audio and video files, and so on. It responds to an error message and can handle errors.

Comparison Table

Parameters of Comparison MAPI SMTP 
Full-Form Message Application Programming Interface Simple Mail Transfer Protocol 
Designed by Microsoft RFC 821 
Released Date 2007 1982 
Functionality It can access messages, files, and various directories. It has functions between servers for the transfer of information. 
Uses It can be used to send and retrieve emails. It can be used to send emails. 
Organization  It organizes mail on local storage. It organizes mail on client storage. 
Support It has less support. It has more support. 

What is MAPI? 

It is a messaging system that Microsoft Outlook and Exchange employ to handle email, meetings, appointments, tasks, and sticky notes, among other things.

It is built on a Microsoft proprietary technology that communicates with a MAPI-based mail server like Exchange using an RPC-based connection.  

It works with various programs, including Send Mail and Send File. It outperforms HTTP in terms of reliability and stability. Regardless of changes to the network connection, it manages to keep the session going.

By employing an HTTP-based protocol, MAPI also provides improved authentication. 

It comes with a standard set of C language functions that are saved in a software library known as a dynamic link library.

It also has a synchronization tool that allows you to sync and view subfolders, custom folders, calendars, and other items across many devices and computers. 

The Messaging Application Programming Interface (MAPI) standardizes how messaging programs manage messages and provides a generic programming interface for building mail-enabled Windows applications.

MAPI also provides an integrated messaging subsystem for Windows that can handle any message transport structure. 

MAPI serves as a link between the messaging software on the computer and the primary message providers.

The user interface for infiltrating these services via MAPI is the same whether the services are LAN-based message services, e-mail services, fax services, or other messaging services. 

What is SMTP? 

Simple Mail Transfer Protocol (SMTP) is a set of communication protocols that allows applications to send electronic mail over the Internet. SMTP is used to establish communication rules between servers.  

The servers have a method of identifying themselves and stating the type of communication they are attempting. They also offer a plan for dealing with problems such as invalid email addresses.

The receiver address, for example, is incorrect. As a result, the server response will contain an error message. 

It’s commonly used for “Mail Relaying,” which involves routing email from one SMTP server to another to reach its target. It also allows you to check for mistakes in messages and take action in response to them.

It stipulates various conditions for mail forwarding, one of which is that the user’s email address must be changed. SMTP servers provide characteristics that allow them to be used as an email gateway.  

SMTP is an end-to-end delivery method in which an SMTP client computer sends mail directly to the destination host’s SMTP server.

Only the mail-gateway host is supported by SMTP, not the actual destination host, located outside the TCP/IP network.

The SMTP end-to-end transmission in the mail gateway is either host to a gateway, gateway to host, or gateway to gateway. The structure of mail is determined by the gateway, not by SMTP. 

Simple Mail Transfer Protocols represent a client/server protocol. The session is initiated by the client SMTP device sending an SMTP message, and the mail server responds by accepting an SMTP message in response to the session request. 


Main Differences Between MAPI and SMTP 

  1. MAPI stands for Message Application Programming Interface, and SMTP stands for Simple Mail Transfer Protocol. 
  2. MAPI was designed by Microsoft in 2007, and SMTP was designed by RFC 821 in 1982. 
  3. MAPI has functions to access messages, files, and various directories, and SMTP has functions between servers to transfer information. 
  4. SMTP can only be used to send emails. However, MAPI can be used to both send and retrieve emails. 
  5. MAPI organizes your mail on local storage, whereas SMTP organizes your mail on client storage. 
  6. MAPI has had less recognition and support than SMTP, which has gotten more support. 

Last Updated : 17 August, 2023

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