Gmail is shutting down its POP-based mail fetching feature later this year. If your mail lives on a server you can SSH into, here's a simple replacement: a procmail recipe pipes each incoming message to a small Python script that uploads it to Gmail via IMAP.No polling, no cron jobs - mail arrives in Gmail the moment it hits the server.
https://nosuch.biz/mailsync/
Code: https://github.com/bwagner/gmailsync