[SOLVED] Relaying Failre

[infinityM]

Hey Guys,

I am running Proxmox Mail Gateway with multiple servers.
One of which is a direct admin server, Which is using it as a smart host to send mails aswell, and it's running smooth as silk.

When I tried connecting the new Exchange server to the PMG as a SmartHost, I am seeing errors in the log.

The first of which was Relay access denied errors. Which went away when I changed the exchange smtp port to send through port 26. But now I am seeing errors in the logs like:
Mar 28 12:53:00 pmg postfix/smtpd[1528]: NOQUEUE: reject: RCPT from unknown[156.38.200.57]: 451 4.3.0 <xxx.xxx@gmail.com>: Temporary lookup failure; from=<test@mydomain.com> to=<xxx.xxx@gmail.com> proto=ESMTP helo=<INFEXC01.dom.cloud>

I don't know if it makes a difference, but the domain "INFEXC01.dom.cloud" does not actually exist. It's just the cluster's internal domain for exchange

What can I check to resolve this? It's frustrating me to no end...

 

[Stoiko Ivanov]

have you added your Exchange's IP to GUI->Configuration->Mail Proxy->Networks?
That should help with that.

 

[infinityM]

have you added your Exchange's IP to GUI->Configuration->Mail Proxy->Networks?
That should help with that.

I did do that. The only problem then was that all mail relaying to the other server started failing somehow?

 

[Stoiko Ivanov]

I did do that. The only problem then was that all mail relaying to the other server started failing somehow?

how did they fail?
please provide some logs

 

[infinityM]

how did they fail?
please provide some logs

That's the thing... I am not sure which logs to check. From what I can see I can't see the connection in the logs. But I can't see a reason for the server being unable to send the mail to proxmox....

 

[Stoiko Ivanov]

I am not sure which logs to check.

for PMG the relevant logs should be /var/log/mail.log (and possibly the general journal - `journalctl -b` )
for the other systems - if they are unix-like - /var/log/mail.log would be a good starting point as well

 

[infinityM]

for PMG the relevant logs should be /var/log/mail.log (and possibly the general journal - `journalctl -b` )
for the other systems - if they are unix-like - /var/log/mail.log would be a good starting point as well

Ok so I played around and this is the issue I am now getting again...

When I send an email to an email address who's domain is local (the routing is in my PMG) it does route correctly.
When sending to gmail I see the below lines:


Apr 6 17:45:53 pmg postfix/smtpd[131709]: warning: hostname infexc01.myhostname.tld does not resolve to address 156.38.200.x: Name or service not known
Apr 6 17:45:53 pmg postfix/smtpd[131709]: connect from unknown[156.38.200.x]
Apr 6 17:45:53 pmg postfix/smtpd[131709]: NOQUEUE: reject: RCPT from unknown[156.38.200.x]: 554 5.7.1 <mygmailaddress@gmail.com>: Relay access denied; from=<test@mydomain.com> to=<mygmailaddress@gmail.com> proto=ESMTP helo=<INFEXC01.myhostname.cloud>
Apr 6 17:45:53 pmg postfix/smtpd[131709]: disconnect from unknown[156.38.200.x] ehlo=2 starttls=1 mail=1 rcpt=0/1 quit=1 commands=5/6

And the bounce imediately comes when sending in outlook as below:

Remote Server returned '554 5.7.1 <mygmailaddress@gmail.com>: Relay access denied'

Email was sent from test@mydomain.com to mygmailaddress@gmail.com so the outbound proxy is blocking it. Inbound emails are relayed to the domain correctly though?

I hope that helps?
Also the sending server is a hosted exchange 2016 server hope that helps...

 

[Stoiko Ivanov]

do you have enabled 'reject unknown clients' or 'reject unknown senders' in GUI->Configuration->Mail Proxy->Options?
does your exchange relay over the internal port (26) or the external port (25)?

also check that your pmg's dns config is working (i.e. hostnames can be resolved)

 

[infinityM]

do you have enabled 'reject unknown clients' or 'reject unknown senders' in GUI->Configuration->Mail Proxy->Options?
does your exchange relay over the internal port (26) or the external port (25)?

also check that your pmg's dns config is working (i.e. hostnames can be resolved)

I don't understand how but adding the IP to the networks section this time worked... Thank you anyway guys... I have no idea what fixed it now... I might've changed something else that caused this to work now

 

[Stoiko Ivanov]

Glad that solved itself somehow
please mark the thread as 'SOLVED'
Thanks!