Email Protocols – IMAP, POP, SMTP and Exchange
This guide will provide you with information about the most commonly used Email protocols on the internet – IMAP, POP3, SMTP and Exchange. Read on to see which configuration will best serve your particular email needs.
The Internet Message Access Protocol (IMAP) is a modern mail protocol used for accessing emails by your local client from a remote mail server. IMAP and POP3 are the two most commonly used Internet mail protocols for retrieving emails. Both protocols are supported by all modern email clients and web servers.
While the POP3 protocol assumes that your email is being accessed only from one application, IMAP allows simultaneous access by multiple clients. This is why IMAP is more suitable for you if you’re going to access your email from different locations or if your messages are managed by multiple users.
By default, the IMAP protocol works on those ports:
- Port 143 – this is the default IMAP non-encrypted port
- Port 993 – this is the port you need to use if you want to connect using IMAP securely
Post Office Protocol version 3 (POP3) is a standard mail protocol used to receive emails from a remote server to a local email client. POP3 allows you to download email messages to your device and read them even when you are offline. Note, that when you use POP3 to connect to your email account, messages are downloaded locally and removed from the servers. This means that if you access your account from multiple locations, that may not be the best option for you.
By default, the POP3 protocol works on two ports:
- Port 110 – this is the default POP3 non-encrypted port
- Port 995 – this is the port you need to use if you want to connect using POP3 securely
Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending emails.
By default, the SMTP protocol works on three ports:
- Port 25 – this is the default SMTP non-encrypted port
- Port 2525 – this port is an alternate SMTP non-encrypted port
- Port 465 – this is the port used, if you want to send messages using SMTP securely
- Port 587 – this is an alternate secured SMTP port
Exchange is a Microsoft specific mail service, and it uses multiple legacy, proprietary and standard protocols, for both sending and receiving emails.
All the ports mentioned above for IMAP, POP3 and SMTP can be used by Exchange. In addition Exchange service may require web ports:
- Port 80 – this is the default web port
- Port 443 – SSL secured web port – more commonly used for Exchange