you mean Marshy? 
- Fountain-San
Marsh and Stewart are among those who don't mind strangers calling them by the nicknames as an alternative to their given names.
My preferred form is to use first names unless the other person uses the nickname freely. Always best to start with something more formal. Even then, it all depends on the person and their preferences.
Brad Marsh named his former Ottawa restaurant "Marshy's" and gladly answers to it if someone calls him by the nickname. Brian Propp "signs" his emails as Propper even if you call him Brian in the salutation on your end of the correspondence. So I do now use Propper for Propp, for example. Bob Kelly in any hockey-related context gladly still answers to Hound and uses it himself.
On the other hand, the couple of times that I've contacted former Flyers and Rangers goalie Bob Froese, who is now an ordained minister, I would only ever call him Rev. Froese or Bob out of respect. I would never feel comfortable calling him"Frosty" even if he said he didn't mind it.
