Net2Phone may be the answer in that case. If it's offered and you don't sound like a squeaky wheel, take advantage of it - it makes your ad stand out and many people are more aural than visual. If someone replies to your ad, they do it through the service - your email address isn't given out. It's then up to you if you want to respond to them or not. With some services however, if you respond to someone else's ad, your email address is sent to them with your reply.
Ads can be out of date.
That's why the email notification is so useful - you only get details of new ads. No checking is done. Provided they're not considered obscene or inflammatory, ads will be posted exactly as submitted. You have no idea if the photo is of the advertiser or whether they are telling the truth about themselves or not. We're working on a Safety section for advice on how best to check people out, keep your details confidential and generally be safe until you're sure of who you're corresponding with.