Mail Protocols

Mail Protocols, Unit 4

IT 273 Networking Concepts

The protocols known as SMTP, POP3, and IMAP are internet protocols that have to do with sending and receiving emails. They have some similarities but are quite different from each other. Determining the best one(s) to use for a business depend on the organization needing to make that choice. The clients used for accessing the emails may also have something to do with which protocols will be used. SMTP is the standard for sending emails, while POP3 and IMAP are used for receiving. POP3 removes the emails from the server, while IMAP leaves them on the server so they can be accessed anywhere.

SMTP, or Simple Mail Transfer Protocol, is an internet protocol responsible for sending emails across the internet from one computer to another system. SMTP is responsible for packing up the email to be sent and pushes it out to another email client that the receiver uses. It also forwards the email to another server if the one to be receiving is a different client. So sending from one Gmail account to another does not require a forwarding system, however, a Gmail account to an MSN account requires being sent to another server entirely.

POP3, or Post Office Protocol version 3, is used to receive the email from the server. As the name suggests, this protocol acts much like a postman. The POP3 protocol of a program, such as Thunderbird or Microsoft Outlook, goes to the email server and requests the emails stored for a specific host. After getting those packets, the protocol deletes them from the server and delivers them straight to the program for the user. This protocol is excellent when server space is limited, and emails are only necessary to be accessed in one location.

IMAP, or Internet Message Access Protocol, is another receiving protocol for email. It goes to the server and requests the emails. But instead of taking the only copy there on the server, it takes a copy and returns to the application with the information. This allowed for the user to be able to access the emails on a remote server from any client elsewhere. In a real-world sense, this is like taking a flier and running it across a copy machine before putting the original back to be accessed later. All webmail clients run on IMAP because a user can log in from multiple browsers. An organization that requires access to multiple terminals and access to emails on them would prefer to use IMAP.


SiteGround. (n.d.). Email Protocols – POP3, SMTP and IMAP Tutorial. Retrieved from

Villanueva, J. C. (2015, August 6). SMTP vs IMAP vs POP3 – Knowing The Difference. Retrieved from