Mail slowed down to a crawl...

[Håkon Alstadheim]

Den 15.11.2018 21:00, skrev StarionTech (IMAP):
> 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?

Check server logs for errors. Both dovecot and postfix struggling 
suggest some common underlying cause.

Do measurements  on Cpu, disk, cpu-wait. Which process is hogging the 
server ?  Spam-ass acting up? Drives filling up?

Gut instinct says one or more of your drives are failing, or you have 
file or file-system corruption, so if you are not running smartd, first 
priority is installing smartd/smartmontools and see what falls out.