Let me choose. I'm more likely to decide to buy an upgrade if I like the way you've supported the current version, and I'm much less likely to if you've spammed me. Accept Support Questions Do not autorespond saying you don't take email support questions. If you aren't taking email support questions, you aren't ready to be on the internet at all, please go away until you're in the current decade. Email support is cheaper and more convenient, both for me and for you, than phone support.
Snail mail is unacceptable for the vast majority of problems.
It is required by the RFC's, and it is the first place I will go if I have any trouble sending email to anyone else. If I want a change of venue, I'll suggest it. I haven't got the time to load up the latest set of security holes every time I want some information. Don't rely on graphics. It should work.