POP3, IMAP, and SMTP: Email Differences and Ports
Updated 2 weeks ago
This tutorial will explain 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 best suits your specific needs.
What is POP3, and what are its default ports?
Post Office Protocol version 3 (POP3) is a standard email protocol used to receive mail from a remote server to a local email client.
POP3, together with client software such as Outlook or Thunderbird, allows you to download emails to your local computer and then read them when you do not have an internet connection. Note: when you use POP3 to connect to your mailbox, 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.
It is advisable to use POP3 so that your emails remain stored on your computer, which will reduce the amount of space your email account occupies on the web server (remember that emails tend to take up a great deal of space on the server over time, using up valuable megabytes from your hosting plan).
By default, the POP3 protocol operates on two ports:
Port 110 - the default unencrypted port
Port 995 - the port you need 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 email. 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 it is more convenient to use IMAP when you need to access an account from different devices, and even when certain mailboxes are managed by multiple users.
By default, IMAP operates on two ports:
Port 143 - the default unencrypted IMAP port.
Port 993 - the port you need 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 email over the Internet.
By default, it operates on three ports:
Port 25 - the default unencrypted port
Port 9025 - this port is open on all servers if port 25 is filtered (by your ISP, for example) and you want to send unencrypted email using SMTP.
Port 465 - this is the port used when you want to send email using secure (encrypted) SMTP.