I am using Postfix 3.1.0 and following instructions at
http://www.postfix.org/TLS_README.html#client_smtps to set up for sending
some (recipient dependent) emails via smtps (whereas others go over TLS to
a different relay server). This uses the transport_maps settings in main.cf,
a transport file (hashed) and special routing (relay-smtps) in master.cf.
This works - when the onward smtps server accepts the emails. However in my
case this doesn't always happen - basically they sometimes block when we
are over quota. So when it fails, Postfix falls back using the hosts
specified in main.cf's smtp_fallback_relay (*not* relayhost, which is used
for emails that don't have a match in the transport list).
All well and good. But I find that after smtps rejection, the
fallback_relay hosts (both) always fail too with message like:
warning: TLS library problem: error:140770FC:SSL
routines:SSL23_GET_SERVER_HELLO:unknown protocol:s23_clnt.c:794:
With effect that the email cannot be sent at all.
In short like this:
/etc/postfix/main.cf
transport_maps = hash:/etc/postfix/transport
relayhost = [smtp.sendxxxx.net]
smtp_fallback_relay = [relay.gradxxxx.net] [smtp.sendxxxx.net]
/etc/postfix/transport and /etc/postfix/main.cf - as specified at
http://www.postfix.org/TLS_README.html#client_smtps for Postfix >= 3.0
However if I remove the initial attempt to use smtps (i.e. comment out
transport_maps and reload postfix), then relayhost and fallback_relays work
perfectly.
I've tried a raft of different settings without success. Any suggestions
gratefully received.
Dominic
