A little known fact: Thunderbird email application allows sending emails from the commandline. As MAPI and SMAPI often make trouble, for example the need to repair Office after the last v1709 Win 10 update, to be able to send emails again.
But if you support Mailjob.Provider=“Thunderbird” or “ThunderbirdDirect” you could just call via ShellEx or commandline:
Start Thunderbird -compose “to=user@domain.com,subject=Greetings from LL,body=Hello world,attachment=C:somereport.PDF”
You can even provide a html-file instead plain text (note: using message instead of body!):
Start Thunderbird -compose “to=user@domain.com,subject=Greetings from LL,message=C:message.html,attachment=C:somereport.PDF”
In this case message.html looks like: Hello world!
More information and commandline options: Firefox/CommandLineOptions - MozillaWiki
In the long run this even helps making LL more independent from Microsoft and more platform agnostic. For an easier migration from LL to Linux in the long run…