POP3 is the most up to date version of the Post Office Protocol, and it lets email applications retrieve email messages from email servers. This means that wherever you access a web-based email service you can get at your mail.
POP3 is one of several standard email retrieval protocols and its supported by the majority of email apps and web services. POP3 lets you access your emails so you can read them online or save them off-line, but one of its features is that your messages are deleted as soon as you’ve looked at them. POP3 can be made secure using an encrypted connection with STLS, TLS or SSL.
The POP3 protocol is simple and widely supported so it works with online services like Gmail and Hotmail and clients such as Thunderbird and Outlook
When you log in to access your email using POP3, you need to remember that your messages will be downloaded to whatever device you are using the time. So, once they’ve been deleted from the POP3 server, they will only exist on your device, most email clients you could set received messages to remain on the server for a longer period.
For sent messages, POP3 sends them but doesn’t save them to your local Sent email box. It typically uses the 110 port and the 995 port when the connection is encrypted.
POP3 vs IMAP
Both the POP3 and IMAP protocols are widely supported for email retrieval. Of the two, IMAP is the newer and more adaptable one, and it’s usually the protocol of choice. IMAP leaves emails on the server automatically, so the user will always have them until they choose to delete them. This means you don’t need to fill your hard disk (or disks on different machines) with emails, and they are always safe and accessible. As long as you have a connection, a browser or a webmail client you can get at your email messages from anywhere.
This suits corporate or educational email accounts that need to be available to many people. Overall, IMAP has more options for managing emails, for the best of both worlds using IMAP and POP3 covers everything.