Am 11.09.2013 20:19, schrieb Jeroen Geilman: > On 09/09/2013 09:27 PM, Wietse Venema wrote: >> Postfix does a hard bounce when the DNS server replies that the >> name has no MX record AND the DNS server replies that the name has >> no A record, AND (if Postfix IPv6 support is on) the DNS server >> replies that the name has no AAAA record. > > Does that mean that postfix will do a hard bounce if there is no reply to an > MX query after a timeout ? > I thought it would at least try the other queries (A and/or AAAA) before > giving up, since this costs no more than > when there /is/ a (negative) reply. > > Since postfix may be talking to a cache or a resolver with numerous hops in > between postfix and the authoritative > source, any of the queries may fail individually, and yet not be conclusive. > >> Postfix does a soft bounce when any of those lookups does not produce >> a reply. > > This seems to suggest the former, but I am double-checking
* no reply -> defer -> soft bounce * NEGATIVE reply -> no defer -> hard bounce this answsers all possible cases because timeout is also "no reply" if a domain does not exist because the worldwide DNS recursion says "there is no such domain, there is no nameserver to ask" it would be pointless to soft bounce / defer and hope someone registers the domain a outage is by definition "no reply"
