[Dovecot] FreeBSD, Dovecot and ZFS

[Jason Lock]

Mail Issues - FreeBSD

Hello, my apologies if this may be the wrong forum but hoping that maybe someone might be able to provide some insight.

Have a very sporadic and strange issue with our mail servers running Dovecot on FreeBSD.  There are three servers hosting Dovecot with FreeBSD as the underlying operating system.  All three connect to a NAS server, again running FreeBSD and ZFS.

When the specific issue occurs, clients connecting to check mail via POP3 or IMAP experience long delays and timeouts.  To the point where POP3 Logins fail due to the timeouts.  The issue is further compounded by clients increasing the number of attempts to check mail.

Part of the frustration in attempting to diagnose the issue is not knowing the root cause or symptom that initates the issue.

Wondering if anyone has experienced anything similar, or suggestions on ways to help identify the root cause