I'm sure there's a check box during the registration process that's along the lines of "Allow users to contact me by email".
Maybe..just found it a bit strange...I've been getting emails saying I'm interested...can u call me blah blah
I've never had this before so just thought It may be a scam of sorts...as mentioned genuine buyers tend to use the pm facility on the site imo
Do the emails show their user name? You're not wrong in being cautious. It's probably fine, but to assume everyone is honest is a bit of a mistake, so I can't blame you.
Ultimately, as long as it's a cash deal and you don't let the wheels go until the cash is in your hands, you'll be ok. You do need to be careful with things like Paypal, delivery etc, it opens the door for so many different scams.
Does the wording of the emails sound dodgy?