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New Member

SMTP Port on PIX


I have my PIX 515-E up and running fine. My Excahnge server is sending and recieving e-mail through the firewall with no problems.

I now want to set up a Event Sink on the server to append a disclaimer to all outgoing e-mails. According to Microsoft Knowledge Base article Q288756 I need to set up a second SMTP virtual server to send e-mails on port 26! Obviously the firewall is allowing SMTP traffic through on port 25.

My question is How do I tell the Firewall to allow SMTP traffic on port 26 instead of 25??

Any help much appreciated.



New Member

Re: SMTP Port on PIX

If you have an access-list restricting traffic outbound from the interface that the exchange server is on:


access-list permit tcp host any eq 26

This will allow TCP port 26 to talk to any host, which is required if Exchange is resolving MX hosts to send directly to remote mail servers. If you are using an ISPs mail server as the next mail hop, or a 3rd party mail virus scanning service, then add

access-list permit tcp host host eq 26

To remove the outbound mail permission on port 25:

no access-list permit tcp host any eq 25


no access-list permit tcp host host eq 25

New Member

Re: SMTP Port on PIX

Thanks Chris,

A very comprehensive explanation. I think that the problem is mine though now after reading Kev's reply.

Thanks again,


New Member

Re: SMTP Port on PIX

Hi Robin

From how I am interpreting the article, you shouldn't need to make any changes to the firewall. The first exchange server will effectively forward any mail that needs to be sent externally to your new virtual server on port 26, which fill fire the Transport Event on the message and then forward it out on to the internet on the normal SMTP port 25 through the firewall. The original server will still be receiving email just as it has on port 25.



New Member

Re: SMTP Port on PIX

Thanks Kev.

You are probably right. Now that I have read the article again this does seem to be the way it works.