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 on your local computer 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 email server. This means that if you access your account from multiple locations, that may not be the best option for you. On the other hand, if you use POP3, your messages are stored on your local computer, which reduces the space your email account uses on your web server.
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
The Internet Message Access Protocol (IMAP) is a mail protocol used for accessing email on a remote web server from a local client. 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.
IMAP also provides the user more capabilities for retaining e-mail on the server and for organizing it in folders on the server. IMAP can be thought of as a remote file server.
By default, the IMAP protocol works on two 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
POP and IMAP deal with the receiving of e-mail and are not to be confused with the Simple Mail Transfer Protocol (SMTP), a protocol for transferring e-mail across the Internet. You send e-mail with SMTP and a mail handler receives it on your recipient’s behalf. Then the mail is read using POP or IMAP.