I am starting to see a certain type of email that is causing problems for our users. I am running sendmail on Fedora with mimedefang-filter. When this certain type of spam comes in with random characters in the subject and body, it eventually (after several failed attempts) gets put into the INBOX instead of JUNK folder even though it is properly flagged as spam. Dovecot sieve gets confused somehow. Here are the errors in maillog:
Mar 8 03:47:51 afomail sendmail[22473]: v23Hplpr011711: SYSERR(root): timeout writing message to localhost
Mar 8 03:47:51 afomail sendmail[22473]: v23Hplpr011711: to=<username@domain.tld>, delay=4+15:56:03, xdelay=00:00:05, mailer=local, pri=10129675, relay=localhost, dsn=4.4.2, stat=Deferred: Name server: localhost: host name lookup failure
The proper entries are in resolv.conf and this only happens with a tiny fraction of email volume. But something about these emails prevents sendmail from being able to find itself (localhost). How can I fix this?
Contents of nssswitch.conf
passwd: files sss
shadow: files sss
group: files sss
hosts: files dns myhostname mymachines
bootparams: nisplus [NOTFOUND=return] files
ethers: files
netmasks: files
networks: files
protocols: files
rpc: files
services: files sss
netgroup: files sss
publickey: nisplus
automount: files sss
aliases: files nisplus
hosts:
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 mydomain.com
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
results of grep 'D{MTAHost' /etc/mail/submit.cf
D{MTAHost}[127.0.0.1]
Thanks in advance.
