[quote user="Brian Fluet"]The options are to have a single multi-user installation of Pegasus Mail or two separate installations.  In either case the -ms command line option will allow multiple sessions to run.  The caveat is that you can't control which running instance gets invoked by Mailto: and Sendto:.
[/quote]

Well noted, Brian. As both are in care of  wsendto.exe maybe it could ask if two or more instances of Pegasus Mail is running at same time. Just my tuppence.

PS: THANK YOU! Your encouragement got me over a hurdle I was struggling with. For more on this subject, see the thread I started the same day as this called "SOLVED: Is "Identities" what I need? Other solutions?"

Is there some trick which would allow me to have two separate instances of PMail running concurrently on one Windows 10 PC?

(They would connect to their mail servers via POP/SMTP, and always to different accounts on the servers.)

Would it in any way be a "bad idea"?

Preferably using PMAIL v4.73, but I'd do a reinstall/ upgrade, if necessary.

We are using Pmail in connection with Mercury, where local user accounts are created/managed by Mercury. We are able to run different concurrent Pmail sessions at the same time at the same computer for different local users. I have only to start Pmail with the options -ms and -i , means winpm-32.exe -ms -i <localuser>. But don't know whether it works also with a stand alone installation of Pmail.

The options are to have a single multi-user installation of Pegasus Mail or two separate installations.  In either case the -ms command line option will allow multiple sessions to run.  The caveat is that you can't control which running instance gets invoked by Mailto: and Sendto:.