I recently upgraded to a Sonicwall ES300 email security device. Previously we were using the software version of this. In running this the software was using port 25 as the inbound port and then forwarding processed mail to port 2525. Outbound mail was setup to run on port 2526. Now that the new device has been installed and the software shutdown we are running into issues with mail from some hosts not getting through because they are looking for port 25 on the mail server and the spam software has been shutdown so port 25 is no longer active. The active port for the default smtp server is currently 2525 and so internal mail cannot get there unless we change all the ports on all the software.
I would like to know if it is possible to run another smtp connector on port 25 in parallel with the default on port 2525 and then slowly move all the other services to port 25 as we need? Or would the best issue be to change the default to port 25 and take mail down until I can get all the other services moved to 25?