Powershell.exe -executionpolicy remotesigned -File C:\Smartermail\ExportCert.ps1

//* MAKE SURE to modify the 3 areas that require it: mail domain, password and path to the PFX on your server 

(Get-ChildItem -Path cert:\LocalMachine\My |
Where-Object {$_.Subject -match "mail.mydomain.com"} |
Sort-Object -Property NotAfter -Descending |
Select-Object -first 1) | Foreach-Object {&certutil.exe @('-exportpfx', '-f', '-p','mypassword',$_.Thumbprint, "C:\SmarterMail\mail.mydomain.com.pfx")}