How often should I check for new mail?
Most POP email programs let you choose how often the program should check for new messages in a mailbox.
If you use this feature, don’t set it to check more than once a minute. If you do, some connections may be rejected to limit the load on our mail servers.
If you receive large amounts of email and need to check more than once a minute, we suggest using IMAP connections instead. Mail programs that use IMAP make a single persistent connection instead of many small connections.