I configured Postfix for some virtual domains. When I inspect the headers of messages delivered via my server, one of these domains appears as part of the "Received" header":
Received: from actual.hostname.tld (virtual.domain.tld [1.2.3.4])
Why does virtual.domain.tld appear in this header? It is always the same domain, although Postfix' main.cf contains 9 virtual_alias_domains
.
It is a reverse DNS query
virtual.domain.tld
is surely the PTR record for 1.2.3.4Try:
dig -x 1.2.3.4