Here are the steps to have Imail and Hexamail coexist:
Move Imail to another port
1) Run the Windows Registry Editor. Choose Run from the Windows start menu and then type regedt32.exe
2) Locate the registry entries for "HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ SMTPD32 \ Parameters"
3) Click on this folder, and several fields such as "Version" and "AcceptAny" will appear on the right window in the Windows Registry Editor
4) Choose the "Edit \ Add Value" menu option
5) For "Value Name", enter "Port" (remember to capitalize the P in Port), for "Data Type" choose REG_DWORD
6) A window will pop up asking for a value. Choose "decimal" as the "Radix" in the window and type "2500" in the "Data" field
7) You should now see a new value which says: "Port: REG_DWORD " 0x9c4
8) Go to the "services" control panel, then stop and start the "Imail SMTP Server" service
9) Imail is now configured to listen to port 2500
Install and Configure Hexamail
1) Install Hexamail
2) You will now need to set the SMTP Server setting in Hexamail. If you are installing Hexamail on Windows, the setup program will ask you for the TCP/IP and port of your mail server during the configuration Wizard, or you can change this by opening the administration interface and setting the port on the SMTP Server settings page.
3) Next, set Hexamail SMTP Relay settings to point to your newly configured port.