Installing Alligate on Mail Servers

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We always recommend that Alligate be installed on a dedicated computer. Alligate will always perform best when it does not have to compete for memory, CPU, disk access and other system resources. We officially do not support Alligate installations when it is installed on the same machine as the mail server itself. We can offer no particular expertise for any specific mail server product, and cannot offer support for resolving issues related to same server installation.


However, many Alligate users do install Alligate on the mail server computer and use it very successfully. As far as we know, it can be done with almost any Windows mail server product except Microsoft Exchange. If you choose to do this, please keep in mind that we will not be able to provide support for working out compatibility issues. There are a few basic concepts to keep in mind as outlined below.


Alligate listens on the SMTP port (port 25). Your mail server also listens on the same port. You cannot have both Alligate and your mail server listening on the same port.


There are a couple of methods for dealing with this.


You could set your mail server to listen on a different port, say 2525. You can then have Alligate listen on port 25 and relay incoming email to port 2525 on the localhost address. This can be defined in the Alligate Gateway Configuration program in the routing definition section.


There may be a potential problem with this however. Some mail servers with integrated web mail will try to send message sent from users using a web interface on the standard SMTP port 25 and expect port 25 to be answered by the email server, not Alligate. We have heard of various issues related to this and it is difficult if not impossible to resolve in many situations.


The recommended way to do this would be to leave your mail server running on port 25. Then configure Alligate to listen on a different port, again, let's just say port 2525. This can be defined in the Alligate Gateway Configuration program in the network settings section.


You could then configure your router or firewall to forward all incoming SMTP port 25 traffic to Alligate on port 2525. This method will require no changes to your mail server configuration at all. Of course, this capability needs to be supported by your router or firewall and you would need to check with the manufacturer or the technician who would normally be in charge of maintaining your router or firewall. We cannot offer any help in this area.


One final caveat to installing Alligate on the mail server. When setting up your routing definition for delivery to your mail server, it may seem logical to define the destination server address as (localhost). This does not always work. You should check your mail server settings to see what IP address(s) the mail server is specifically bound to. It is not uncommon for the mail server to be bound to a specific IP address assigned to that computer. If it is, you will need to define the destination server as an IP address the mail server has created bindings for.