My machine (CentOS, sendmail-8.14.7-5.el7) accepts emails from machines and forwards all of them to my smarthost
my-smarthost.mydomain.com, which in turn has several dynamic MX-records). Local mail stays local (using the alias-file).
sendmail.mc: define(`SMART_HOST', `smtp:my-smarthost.mydomain.com')dnl
Today I noticed a problem:
# mailq /var/spool/mqueue (1 request) -----Q-ID----- --Size-- -----Q-Time----- ------------Sender/Recipient----------- 02AG1YBC023172 1239 Tue Mar 10 17:01 <email@example.com> 8BITMIME (host map: lookup (non-domain.com): deferred) <firstname.lastname@example.org> # sendmail -v -q Running /var/spool/mqueue/02AG1YBC023172 (sequence 1 of 1) non-domain.com: Name server timeout <email@example.com>... Transient parse error -- message queued for future delivery
Why does sendmail try to dns lookup the addresses inside the mails? I thought it just forwards everything non-local to the smarthost!
I tried to use the trick to disable DNS-lookup with
and so on, but there is a problem with that: This also disables the MX-search for the smarthost! So the dynamic MX-records for my smarthost are no longer found/used!
Any ideas how to stop sendmail from doing anything except relaying to the smarthost?