A winmail.dat attachment is the result of a Outlook sending messages in it proprietary RTF format. Configuration by the sender can fix this. Good luck with convincing them to do that though. While I was employed I spent a good bit of time attempting to convince email senders (employees of vendors, financial institutions, insurance providers, and the like) to configure their Outlook to be considerate of non-Outlook recipients. I rarely got anywhere because our business was the only one reporting a problem. I ended up putting Winmail Opener on every PC and training users on its use.
smime.p7m attachment is the result of the sender digitally signing their email. Outlook can handle smime.p7m attachments, Pegasus Mail can not. I don't know of a way to handle them other than with an external utility as you are doing.
A winmail.dat attachment is the result of a Outlook sending messages in it proprietary RTF format. Configuration by the sender can fix this. Good luck with convincing them to do that though. While I was employed I spent a good bit of time attempting to convince email senders (employees of vendors, financial institutions, insurance providers, and the like) to configure their Outlook to be considerate of non-Outlook recipients. I rarely got anywhere because our business was the only one reporting a problem. I ended up putting Winmail Opener on every PC and training users on its use.
smime.p7m attachment is the result of the sender digitally signing their email. Outlook can handle smime.p7m attachments, Pegasus Mail can not. I don't know of a way to handle them other than with an external utility as you are doing.