POP3, IMAP, and SMTP: Email Protocol Differences and Ports
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This tutorial explains the most widely used email protocols on the Internet: POP3, IMAP, and SMTP. Each has specific functions and ways of working. Keep reading to learn which configuration is right for your needs.
¿What is POP3 and what are its default ports?
Post Office Protocol version 3 (POP3) is a standard email protocol used to receive email from a remote server on a local email client.
POP3, together with client software such as Outlook or Thunderbird, lets you download emails to your local computer and then read them when you don't have an internet connection. Note: when you use POP3 to connect to your email account, messages are downloaded locally and removed from the online server. This means that if you access your account from multiple locations, it may not be the best option for your needs.
Using POP3 is useful for storing your emails on your computer, which reduces the space your email account uses on the web server (keep in mind that emails tend to take up a lot of space on the server over time, using up valuable megabytes from your hosting plan).
By default, the POP3 protocol uses two ports:
Port 110 - the default unencrypted port
Port 995 - the port to use if you want to connect using secure (encrypted) POP3.
¿What is IMAP and what are its default ports?
The Internet Message Access Protocol (IMAP) is an email protocol used to access your emails on a remote server from a local client. IMAP and POP3 are the two most commonly used protocols for receiving emails. Both are supported by all modern email clients and web servers.
While POP3 assumes that your email will be accessed from only one application (e.g., Outlook), IMAP allows simultaneous access from multiple clients. This is why IMAP is more convenient when you need to access an account from different devices, or when multiple users manage certain email accounts.
By default, the IMAP protocol uses two ports:
Port 143 - the default unencrypted IMAP port.
Port 993 - the port to use if you want to connect using secure (encrypted) IMAP.
What is SMTP and what are its default ports?
Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending emails over the internet.
By default, it uses three ports:
Port 25 - the default unencrypted port
Port 9025 - this port is open on all servers in case port 25 is blocked (by your ISP, for example) and you want to send unencrypted emails using SMTP.
Port 465 - this is the port used when you want to send emails using secure (encrypted) SMTP.