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Windows Ninja
Asked: 2012-03-21 11:26:00 +0800 CST

How do I configure PostFix to allow other machines to send out email through it?

  • 772

I have PostFix up and running on a CentOS box and would like to send mail from a Windows server on the same network out through the PostFix server.

When I try to telnet from the Windows server into port 25 on the PostFix server currently the connection fails.

Where do I set this up within PostFix/CentOS?

Thanks in advance!

postfix

3 Answers

  1. Best Answer

    You will need to configure relay. However when postfix is running you should be able to still connect to port 25. Might there be a firewall blocking this connection?

    When you open main.cf, you can need to add this directive:

    mynetworks=A.B.C.D

    example:

    mynetworks = 127.0.0.0/8 168.100.189.0/28
mynetworks = !192.168.0.1, 192.168.0.0/28
mynetworks = 127.0.0.0/8 168.100.189.0/28 [::1]/128 [2001:240:587::]/64

    do not put 0.0.0.0 or you will become an open relay.

    • 25

  2. My Postfix server has something of the sort in its IPtables to enable connections.

    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:25

    Your server might be restricted even further, depending on what you are trying to do. But if telneting to it on port 25 fails do not expect the machine to function as an SMTP server (unless of course you change the ports - which is not what you said). Note that it is possible, many time preferable to accept connections on other ports.

    • 0

  3. @LucasKauffman is correct, mynetworks is the way to go --- but be sure that smtpd_recipient_restrictions has permit_mynetworks, something like this:

    smtpd_recipient_restrictions = permit_mynetworks, ...

    This is the default, but if you have -o smtpd_recipient_restrictions=something on an smtpd line in master.cf then it will override main.cf setting.

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