Postfix Temporary lookup failure

Solution 1:

mynetworks needs strict network ranges

In my case, there was a wrong ip range in /etc/postfix/

# Wrong; Temporary lookup failure
mynetworks =
# OK
mynetworks =

There was an error in /var/log/maillog that I noticed later.

Oct 4 13:47:54 postfix/smtpd[25056]: warning: non-null host address bits in "", perhaps you should use "" instead

If someone comes here from the top hit on google with searching Temporary lookup failure, I'd say please dubble-check your $mynetworks format.

Solution 2:

Run newaliases . If /etc/aliases doesn't exist then create it first, then run newaliases .
Also maybe update/add alias_maps = hash:/etc/aliases to /etc/postfix/ to get rid of the other warning.
Then try again.
(If you test with telnet, you don't need working DNS).

2nd issue: First remove $myhostname, $mydomain, from mydestination, since virtual domains shouldn't be listed here.
Then add (to

Reload postfix and try again.