Hi Robert Mathias!
I completely agree with you that if I send an .MSG attachment this should remain so and not change the format and / or extension, also because this could lead to disputes (even legal) because the email sent is physically different from the one that is then receipt...
That said, my Outlook has no issue opening EML files processed by SmarterMail.
What version of Outlook are you using?
Gabriele Maoret - Head of SysAdmins at SERSIS
Currently manages 6 SmarterMail installations (1 in the cloud for SERSIS which provides services to a few hundred third-party email domains + 5 on-premise for customers who prefer to have their mail server in-house)