lmtpd timeout

[Gregor Bruhin]

> It should decrease peak load of cyrus generated by sendmail deliveries.

The cyrus backend server has a few thousand mailboxes, and four frontents
are sending quite a lot of mails but the load on the backend is really low.

> Have you considered making sendmail "chain" deliveries to cyrus via LMTP ?
> * multiple messages over single LMTP connection
> * a small delay before delivery (<30s for most messages)

Bypassing the problem by openning fewer lmtp connection is your idea.
Actually the mta's execute custom filters per recipient, using mimedefang
and stream_by_recipient feature, so each message generates a new lmtp
connection. I think there is no way to optimize that in these conditions no
?

> [make cyrusv2 "expensive", make it use a separate queue group, use
persistent
> queue runners, use MinQueueAge (delay *between* delivery attempts]

The idea is to requeue messages to be delivered to cyrus in a separate
queue, in order to group the delivery via lmtp ??? It is more an mta problem
(off-topic here) but I don't know if/how I could tell sendmail to send
multiple differents mails over one lmtp connection...

Thanks Greg