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POP3 clients connect to the server at specified intervals and download all of a user’s messages without leaving copies on the server by default.
Most servers and clients support both IMAP and POP3.Setting up the software is tricky, filtering spam can be difficult, and keeping everything running smoothly is challenging.You should carefully consider all of your options before deciding to run a mail server.IMAP and POP3 both have secure versions (IMAPS and SSL-POP) which use SSL encryption for mail transfer. Here are the most popular IMAP and POP3 servers available: An SSL certificate encrypts connections to your mail server.It’s possible to run a mail server without an SSL certificate, but it’s not recommended.
Different MTAs support different types of mailboxes.