Google lets you access your Gmail messages via the Post Office Protocol (POP), also known as POP3, through a third-party application. To use POP with Gmail, first enable the service and then adjust the settings to meet your needs. You can start reading messages on supported email clients once you have POP access set up on Gmail.
You can enable POP access in Gmail quite easily through the "Mail Settings" screen. To get there, click the "Gear" icon at the upper, right corner of the Gmail website and click the "Mail Settings" link. On the next page, click the "Forwarding and POP/IMAP" tab. Go to the "POP Download" section and then click the "Enable POP for All Mail" radio button. Click the "Save Changes" button. You have successfully enabled POP access on your Gmail account.
You are finished with setting up POP access on Gmail, but you still need to configure your third-party email client. Each client setup process is different, but should follow a similar chain of steps. After you launch the email client, go to the screen where you add a new email account. For the incoming mail server, set it to read "pop.gmail.com" on port "995" with SSL encryption enabled. For the outgoing server, set it to read "smtp.gmail.com" on port "465" for SSL and port "587" for TLS. As well, set it to use authentication if given the option. The login credentials are the same as your Gmail account, but make sure you provide the full email address as the username.
Google recommends using supported email clients to access your messages via POP. The list includes Apple Mail, Outlook Express, Outlook 2003, Outlook 2007, Mozilla Thunderbird, Windows Live Mail and the iPhone. Other clients may be supported; check documentation provided by the application's developer to see if it supports POP access.
The Instant Message Access Protocol (IMAP) is another protocol that Gmail supports. In fact, Google recommends IMAP over POP and you may want to consider using it. The difference between POP and IMAP is that IMAP offers a two-way communication between the email application and Google's email service. On the other hand, POP downloads messages from the Gmail servers, but doesn't communicate changes back to them. For instance, if you delete a message in your email application, it doesn't get deleted from the Gmail servers. It remains in your inbox until you log into the Gmail Web-based interface.