Hi,
We're migrating our mailboxes from Zimbra to dovecot, running on FreeBSD 12.2. We're using mdbox and solr for fts. dovecot version 2.3.17.
One of our mailboxes gets a bcc of every outgoing mail from our system and it currently holds ~4.5 million messages taking 30 GB.
One of the ways we use the mailbox is that when outgoing mail is sent,
we store the Message-ID in our database, and in our admin interface we
can open the mail and it's fetched from IMAP by doing a 'SEARCH HEADER
Message-ID
In Zimbra this was reasonably fast, but after migrating the mailbox to dovecot it's 30 seconds which I think we can reduce.
After turning on mail_debug I see this in our log https://pastebin.com/kP9H7gSB
Looks like solr finishes searching instantly, then there's ~30 seconds of silence in the logs, and then more log lines about fetching data from mail cache.
The same thing happens if I use telnet and just issue a 'SEARCH HEADER...' command.
How can I find out what dovecot is doing in those 30 seconds?
.einar