Mail slowed down to a crawl...

Been moving along just fine for a couple years now, then in the last two days, email has slowed to a crawl.

Retrieving email via IMAP is very slow, progress bar in the mail client shows that it is downloading messages almost constantly, like it never closes the connection, or it’s getting the messages very slowly. The server that dovecot/postfix is on has also bogged down to a crawl.

The postfix queue is sitting with hundreds of queued up good customer email.

It’s almost acting like dovecot is not getting the messages from postfix, or they’re being delayed for some reason.

How to approach fixing this?

Jeff J.