What is POP?

Post Office Protocol (POP) is an older mail transport protocol that offers extremely simple email delivery, with no synchronization. Additionally, the POP protocol stores the delivered emails locally, on the computer where the email client is running. If the POP server is configured to delete emails once they have been delivered, this means that if the local email client is lost for some reason, such as a faulty hard disk drive, or a laptop being stolen, then the users email history is gone also.

The major advantage of hosted exchange services over simple POP mailboxes, is in the synchronization features. The POP protocol does not synchronize anything. If a user checks their POP email on one computer, and receives one or more emails, they will only be available upon that computer. If they then move to another computer, and check their email, they will not receive the emails that were sent to the previous computer they were using.

The POP email transport protocol is not a push technology. Users need to instruct their email client to check for new messages (or schedule regular automated checks) to receive new emails.

Overall, the POP protocol has been superseded by both IMAP and Microsoft Exchange ActiveSync. There is no real benefits to be had by using POP as a mail transport protocol unless there is a need to use an older email client or some other device that does not have either Exchange ActiveSync or IMAP support built in.

Most exchange hosting providers do allow their users to connect to the hosted exchange server using the POP protocol. However, they also allow users to connect using IMAP protocol, and this is the much better option as long as the mail client supports IMAP.