Difference between SMTP and IMAP Email Protocols by Lia Infraservices the Leaders in Email Marketing Service in Chennai. To start with, those who are familiar with frequent email correspondence would be aware of the incoming and outgoing email protocols. But you might not be aware of how the incoming (IMAP) and outgoing (SMTP) email is carried on from the server. Let us look in detail at the difference between SMTP and IMAP email protocols. In general SMTP and IMAP are two different email protoc