"Is is possible to transfer mail from my Mac laptop mail client over to
Trisquel?"
Probably, but this isn't the way you want to think of it because it's too
broad and vague and no one can help without further details. More
specifically you want to think of transferring your mail from THIS PARTICULAR
APP in Appleland to this OTHER PARTICULAR APP in Trisquel (because let's face
it there are lots of email programs available on both the Apple side and the
GNU/Linux side.)
So: What program are you using for email on Apple's operating system?
And then: What program are you using for email on Trisquel?
Once that's answered then the better question can be formed: How to transfer
your email from SpecificProgramX to SpecificProgramY?
Once is more-specific question has been formed, there is probably even
information on the Internet about that specific situation. But until that
more specific question has been put together, this a vague and broad topic.
I mean, I could say "Sure; you want to use this particular script to parse
the old UNIX mailbox format into a newer & more modern maildir format, piping
your messages through procmail in the meantime to sort them into various
mailboxes..." but maybe that's not relevant for your situation.
Hopefully you see my point.
