What is the difference between MAPI and SMTP?

Computer NetworkInternetMCA

Let us begin by learning about the Messaging Application Programming Interface (MAPI).


MAPI represents Messaging Application Programming Interface. It is a messaging system that is used by Microsoft Outlook and Exchange for email, meetings, appointments, tasks, sticky notes, etc. It is based on a proprietary technology from Microsoft which uses an RPC-based connection to communicate with a MAPI-based mail server like Exchange.

It includes a standard collection of C language functions that are saved in a program library which is referred to as a dynamic link library. It also supports the synchronization feature by which one can sync and view subfolders, custom folders, calendars, etc. on several devices and computers.

Messaging Application Programming Interface (MAPI) supports a generic programming interface for creating Windows applications mail-enabled and standardizes how messages are managed by messaging applications. MAPI also supports a general messaging subsystem developed into the Windows operating system that can service any message transport structure.

MAPI is a kind of middleman among the messaging software running on the computer and the key messaging services. The user interface for penetrating these services through MAPI is the same whether the services are LAN-based messaging services, e-mail services, fax services, or some other messaging service.


SMTP represents Simple Mail Transfer Protocol. SMTP is a set of communication guidelines that enable the software to transmit electronic mail over the internet, known as Simple Mail Transfer Protocol.

The purpose of SMTP is used to set up communication rules among servers. The servers have a way of identifying themselves and announcing what type of communication they are trying to implement. They also have a technique of handling errors including incorrect email addresses. For example, the recipient address is wrong. Therefore, the server reply will be received with an error message of some type.

SMTP is an end-to-end delivery in which an SMTP client machine contacts the destination host’s SMTP server directly to deliver this mail. SMTP supports only delivery to the mail-gateway host, not to the actual destination host, located beyond the TCP/IP network. In the mail gateway, the SMTP end-to-end transmission is host to the gateway, gateway to host, or gateway to gateway. SMTP does not decide the structure of mail further the gateway.

Each message of the SMTP includes the following field −

  • A header or envelop with a null line terminates that.

  • Contents − Everything after the invalid or blank line is the message body with a sequence of lines containing ASCII characters

Simple Mail Transfer Protocols represent a client/server protocol. The client SMTP device starts the session by mailing an SMTP message, and the mail server responds by taking an SMTP message to the session request.

Published on 18-Nov-2021 05:52:53