====== Exim4 - Slow SMTP ======

DNS is a common issue

Exim may be configured to do an ident lookup on incoming email.  For a long time this defaulted to a 30 second timeout - I'm not sure if this is still the case.  Delaying mail slightly helps a lot with spammers I've found (naive spammers will push the mail anyway, which then lets you trigger on protocol violation errors), so it's worth doing still IMO.

<file>
# RFC1413 lookups can cause timeouts. (ident)
rfc1413_hosts = *
rfc1413_query_timeout = 5s
</file>

**rfc1413_hosts** defaults to *, so if you want to disable it, try

<file>
rfc1413_hosts =
</file>