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Cisco Email Security Appliance

Can the ESA deliver SMTP traffic to a different port number other than 25?

Document ID: 118011

Updated: Jul 18, 2014

Contributed by Chris Haag and Enrico Werner, Cisco TAC Engineers.

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Question:

Can the ESA deliver SMTP traffic to a different port number other than 25?

Port 25 is the standard SMTP port mail exchange servers use to listen for incoming email messages. The ESA can be configured to deliver mail to a specific host over an alternate port. The smtproutes  command in the CLI is the simplest way to configure this:

mail3.example.com> smtproutes

There are no routes configured.

Choose the operation you want to perform:
- NEW - Create a new route.
- IMPORT - Import new routes from a file.
[]> new

Enter the hostname for which you want to set up a permanent route.
Partial hostnames such as ".example.com" are allowed.
Use "ALL" for the default route.
[]> testexchange.example.com

Enter the destination hosts, separated by commas, which you want mail for
testexchange.ironport.com to be delivered.
Enter /dev/null by itself if you wish to discard the mail.
[]> exchange.example.com:1025

Mapping for testexchange.ironport.com to exchange.example.com:1025 created.

There are currently 1 routes configured.

Choose the operation you want to perform:
- NEW - Create a new route.
- DELETE - Remove a route.
- PRINT - Display all routes.
- IMPORT - Import new routes from a file.
- EXPORT - Export all routes to a file.
- CLEAR - Remove all routes.
[]>

> commit

Please enter some comments describing your changes:
[]> testing the new exchange server on an alternate port

Changes committed: Mon Mar 28 14:20:06 2005 PST
mail3.example.com>

In this case, the system is configured to send mail for testexchange.example.com to exchange.example.com over port 1025.

You can also make the above changes via GUI, Network->SMTP Route->Add SMTP Route and fill out the domain and destination host with desired port. You have to submit and commit changes once done.

To configure the ESA to deliver mail to a specific host over an alternate port using the appliance GUI, choose Network > IP Interface and modify the settings of the IP interface.

Updated: Jul 18, 2014
Document ID: 118011