[exim] Exim 4.88: LMTP over TCP timeouts

Hi,

We are using Exim 4.88 on Debian with a non-Debian config. We deliver to
our mailboxes on a separate Dovecot IMAP machine using LMTP over TCP
(SMTP transport). A few times a day we see "Connection timed out" on the
transport. It strikes me as odd that the time between the reception of a
message and the delivery timeout is typically around 20 seconds, whereas
all timeout values are at their defaults, which is 5 minutes for
connect, command and data. Any ideas on this?

Peter