How to prevent MailEnable from conflicting with the Microsoft SMTP Service


How to configure MailEnable so that it does not conflict with Microsoft's SMTP service that is configured with the default installation of Windows.


If both MailEnable and Microsoft's SMTP Services are configured to run on port 25 on the same server, either one of these services could fail and therefore become unavailable.  Only a single SMTP service can listen on port 25. Therefore, the solution is to have the Microsoft SMTP service listen on an alternate port number (example: 26).

Before configuring the Microsoft SMTP service to listen on another port, you will need to disable socket pooling for their SMTP service. Otherwise it will still prevent the MailEnable SMTP service from binding to port 25. To do this you will need to edit the IIS metabase and set DisableSocketPooling to 1 under the /LM/SmtpSvc node. See the following link for more details:

Instructions follow:

1. Open the IIS control panel applet.
2. Expand the tree view to locate "Default SMTP Virtual Server".
3. Right click on this icon and select Properties from the pop up menu.
4. In the General tab, select "Advanced" next to the IP address that the SMTP service is bound to. A new window will open up.
5. Select the IP address. Usually this is called (All Unassigned), but may be a particular IP address. This opens a new window.
6. Change the TCP Port to something other than 25.
7. Accept the changes
8. Stop and start both the Microsoft and MailEnable SMTP services.


CDONTS is not working: Article ME020005

The MailEnable SMTP service does not start: Article ME020006

Product:MailEnable (All Versions)
Class:HOWTO: Product Instructions
Revised:Wednesday, June 20, 2018