Thomas wrote:
Thomas Ackermann wrote:
So, does anybody know what technically is the difference between the
use with and without the signs?
I mean, what network things may happen or not happen?
Nobody knows the technical differences?
:-(
... more likely nobody cares, because postfix behavior is
documented.
When the relayhost is a hostname enclosed by "[ ]" brackets,
postfix asks for an A record and does not ask for an MX record.
If relayhost is an IP address enclosed by brackets, postfix
uses that IP with no additional lookups.
If realyhost is a hostname with no brackets, postfix will
request an MX record, if no MX exists, postfix will then
request an A record.
If relayhost is an IP address with no brackets, postfix will
request a PTR lookup to find the hostname, then request an MX
lookup on that hostname. If no MX record exists, then an A
record is requested for the hostname. Either the MX lookup or
the A lookup may return a result different from the original
bare IP; this is why you should always enclose a literal IP
address relayhost in brackets.
Actual lookups are performed by system libraries, not by postfix.
--
Noel Jones
