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I am currently struggling with the following on a Plesk Plesk server on Debian 9 (where I guess it is OS independent).
I set up a Mail-Gateway (Proxmox Mail-Gateway, called PMG from now on). The plan is, that all incoming mails are first being handled by the PMG to be checked for spam, virus eetc. and, if all checks are okay, are then forwarded to the Plesk server and dealt with further.
Additionally, I want to handle the PMG the outgoing mails instead of using Plesks' postfix instance.
The PMG is not accessible from the public internet, hence it has a private IP, which is 192.168.1.104
However, for testing reasons, I did make it available to the public internet with a public ip, which is A.B.C.D
As on my Plesk server there are multiple domains running, where not for all domains a relaying should be done, I modified my main.cf of Postfix by adding:
The file /etc/postfix/sdr_custom_transport contains
Port 26 in this case is correct, as that's the relaying port from PMG for trusted internal connections.
By doing a
I let the mapping to create.
Now comes the weird thing.
The mapping itself works, however, Postfix is unable to reach 192.168.1.104 and results in a "connection timed out":
However, when I try to connect to this internal IP on port 26 with telnet, it works:
The connection itself works fine according to this. So, I am out of ideas, why postfix ends in a timeout, whereas on the linux shell itself I can connect to there.
For curiosity, when I modify the file /etc/postfix/sdr_custom_transport and change [192.168.1.104]:26 to [A.B.C.D]:26, recreate the map-file, restart postfix and send another email, it is being relayed to PMG, as it should be.
Does anyone here have an idea, why the internal IP does not work where the external one does?
Any help here is highly appreciated! Thanks a lot!
I am currently struggling with the following on a Plesk Plesk server on Debian 9 (where I guess it is OS independent).
I set up a Mail-Gateway (Proxmox Mail-Gateway, called PMG from now on). The plan is, that all incoming mails are first being handled by the PMG to be checked for spam, virus eetc. and, if all checks are okay, are then forwarded to the Plesk server and dealt with further.
Additionally, I want to handle the PMG the outgoing mails instead of using Plesks' postfix instance.
The PMG is not accessible from the public internet, hence it has a private IP, which is 192.168.1.104
However, for testing reasons, I did make it available to the public internet with a public ip, which is A.B.C.D
As on my Plesk server there are multiple domains running, where not for all domains a relaying should be done, I modified my main.cf of Postfix by adding:
Code:
# Sender-based relaying
sender_dependent_relayhost_maps = hash:/etc/postfix/sdr_custom_transport
smtp_connect_timeout = 5The file /etc/postfix/sdr_custom_transport contains
Code:
@domain.org [192.168.1.104]:26Port 26 in this case is correct, as that's the relaying port from PMG for trusted internal connections.
By doing a
Code:
postmap /etc/postfix/sdr_custom_transportI let the mapping to create.
Now comes the weird thing.
The mapping itself works, however, Postfix is unable to reach 192.168.1.104 and results in a "connection timed out":
Code:
May 9 22:21:21 myserver postfix/qmgr[14724]: B5771300958: from=<sender@domain.org>, size=6815, nrcpt=1 (queue active)
May 9 22:21:26 myserver postfix/smtp[17290]: B5771300958: to=<anyrecipient@icloud.com>, relay=none, delay=3360, delays=3355/0.01/5/0, dsn=4.4.1, status=deferred (connect to 192.168.1.104[192.168.1.104]:26: Connection timed out)However, when I try to connect to this internal IP on port 26 with telnet, it works:
Code:
root@myserver:~# telnet 192.168.1.104 26
Trying 192.168.1.104...
Connected to 192.168.1.104.
Escape character is '^]'.
220 securemail1.domain.orgThe connection itself works fine according to this. So, I am out of ideas, why postfix ends in a timeout, whereas on the linux shell itself I can connect to there.
For curiosity, when I modify the file /etc/postfix/sdr_custom_transport and change [192.168.1.104]:26 to [A.B.C.D]:26, recreate the map-file, restart postfix and send another email, it is being relayed to PMG, as it should be.
Does anyone here have an idea, why the internal IP does not work where the external one does?
Any help here is highly appreciated! Thanks a lot!
Last edited:
