What's a legit Russian Email Address?

Okay, off-topic -- but I don't know whom else to ask!

I've recently received an email (for the inn) from a guy purportedly located
outside of Moscow.

I can't seem to reply to him. His address ends in "mail.ru" (as in
) My ISP rejects this as having an illegitimate suffix.
(Apparently the ".ru" is the trouble.)

Is this something I should take up with my ISP? Or did the guy send me an
anti-Spam email address by mistake? What's a legitimate Russian email
address? (He's awaiting my reply!)

Thanks...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"