So, I'm bored at work and thought I'd mention the following. I've never used this site before, so, forgive me.
To one of the answers, you commented afterwards to say:
"OK, I have virtual_mailbox_domains = $transport_maps and transport_maps = hash:/etc/postfix/transport. Inside that file is a line that says condorproperties.co.uk maildrop: - should I delete that line? – DisgruntledGoat yesterday"
then followed it with:
"@Devdas: I've tried deleting that line and restarting Postfix, it doesn't fix the problem, do I need to change "maildrop" to something else? – DisgruntledGoat yesterday"
The answer to your first question is, "yes." That line in /etc/postfix/transport was forcing local maildelivery (via maildrop) for email destined for condorproperties.co.uk. Removing it is most appropriate. The problem is simply restarting postfix is insufficient to apply the change.
The problem is, the map as configured in the configuration file, is a hash:/etc/postfix/transport. The file, /etc/postfix/transport is the human-readable version of the file and should have a corresponding /etc/postfix/transport.db - the compiled hashmap - file as well. You use the command postmap to compile the human-readable version into the hashed version. Postfix does check modification times and should be complaining loudly in your logfiles that /etc/postfix/transport.db is out of date. All you need to do is run postmap /etc/postfix/transport so that the change you made before, (removing the line with the condorproperties.co.uk) to take effect. In fact, I don't believe you even have to do a postfix reload for the change to go live once you've issued the postmap command, but it wouldn't hurt.
Long story short, run postmap /etc/postfix/transport then postfix reload.
Cheers.
Btw, the huge clue in your logfiles was this line:
Jan 6 18:06:52 localhost postfix/pipe[30497]: 0329D3F69: to=, relay=maildrop, delay=0.15, delays=0.1/0/0/0.04, dsn=5.1.1, status=bounced (user unknown. Command output: Invalid user specified. )
notice, halfway through, where it says relay=maildrop?
Assume your mail server name is multiformeingegno.it (myhostname value in postfix) and your server has two IPs 1.2.3.4 and 1.2.3.5 and you are sending a mail from user@otherdomain.tld, setting up all the following is always recommended.
A record of multiformeingegno.it pointing to 1.2.3.4 and 1.2.3.5- PTR record for
1.2.3.4 and 1.2.3.5 pointing to multiformeingegno.it
SPF record for otherdomain.tld should include both 1.2.3.4 and 1.2.3.5otherdomain.tld should have proper MX record or a A record
Hope that was clear. To clarify you one more thing, your system's name has nothing to do here.
Best Answer
Contact the hostmaster at your hosting provider. They should be able to update the PTR record for the IP address they've allocated for your server.
Most providers I've worked with or heard of will gladly help out with this.
Some might be so impudent as to ask for a fee, depending on your existing service level.
In some cases they might refuse to change the PTR value to your mailserver FQDN, because they themselves use it for asset tracking (you would see a long possibly nonsensical value like
host123.dedicated.dc01.dota.customers.hostingprovider.tldor so)If this is the case, simply change your mailservers HELO FQDN to what ever the PTR resolves to.
I believe you can control this using the
smtpd_bannervariable in your postfix configuration.Simply change
$myhostname(or whatever is in there) tohost123.dedicated.dc01.dota.customers.hostingprovider.tldand the Reverse DNS checks will no longer fail