Login to Windows Server
Export SSL Certificate to a Base-64 Encoded Certificate
Connect to your Windows VPS/Server through Remote Desktop where you have installed SmarterMail.
Click Start, select Run. Type MMC, hit enter.
Open File >> Add\Remove Snap ins.
From the list of available snap-ins, select Certificates and hit Add.
A new window will appear, choose Computer account and hit Next.
Ensure local computer is selected and hit Finish >> OK
In certificate tree view, expand Personal and choose Certificates.
Right click on certificate you wish to export >> All Tasks >> Export.
A new window will appear, hit Next.
Select No, do not export private key >> Next.
Save the certificate as Base 64 x509 .cer file >> Next.
Save the certificate at location D:\SmarterMail\xxxxx. Name the certificate and click Save.
Add Ports to Listen Over SSL/TLS (Smartmermail)
Login to SmarterMail as admin user.
Click on Settings icon.
Expand the Bindings folder and click Ports in the navigation pane.
Double click SMTP SSL
Enter Path of Certificate.
Click on Verify Certificate to ensure the certificate exists in the specified path.
Click on Save.
Using above steps, repeat for POP3 and IMAP ports to be encrypted with SSL or TLS.
Restart SmarterMail service.
IIS
Server >> Sites >> Right click smartermail >> Binding >> HTTPS port >> Select new SSL cert >> Restart service