postfix/error[2874]: 1398FA00AC7: to=<foo@mydomain.com>, relay=none, delay=0.12, delays=0.1/0/0/0.02, dsn=4.3.5, status=deferred (delivery temporarily suspended: Host or domain name not found. Name service error for name=postmaster.mydomain.lan type=A: Host not found)

I am unable to figure out why postmaster.mydomain.lan stopped resolving as i can't find out if there was an A record for it to begin with.

postconf -n output:

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
html_directory = no
inet_interfaces = localhost
inet_protocols = ipv4
mail_owner = postfix
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
mydestination = $myhostname, localhost.$mydomain, localhost
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES
relayhost = postmaster.mydomain.lan

Update: Figured this out. A dns record for postmaster.mydomain.lan was overwritten while doing an update to our zone transfer file :/

  • 1
    Can you ping postmaster.mydomain.lan? What does dig postmaster.mydomain.lan ANY return? Check your /etc/resolv.conf file. – Thomas Sep 30 '17 at 8:47
  • @Thomas By default smtp_host_lookup is set to dns. ping uses gethostbyname(3), which is irrelevant. Only dig is useful here. – Satō Katsura Sep 30 '17 at 8:54
  • dig does not return any A record. I have tried the dns server to resolve other internal domains and those work fine. I can't tell what A record was being returned for postmaster.mydomain.lan at some point earlier when this was working. I can't find anything under the dns zone files either :/ – rkrd_10 Sep 30 '17 at 16:23

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