I have a form. The form fields prompt people to include all the information I'll need to respond thoroughly to their question. I'm also able to add a note to clients asking them to file a support ticket rather than use the contact form.
I regularly change the email attached to my contact form (once every few years) because after a few years, spam starts coming to that address. It's an email address that isn't used for anything but that contact form; but spammers still get ahold of the email address and add it to their lists.
I would recommend against using something common like "sales", "presales", "contact", support", or "admin". Those "default" email addresses get added to spammers' lists largely because they know that many site owners will use them, and so they can have a better chance of sending spam off to someone who will potentially click the link (they hope). If you use a particular phrase and then append some numbers to the end of it (one or two, not five or seven), you can rotate that email address at need but still keep most of it the same. This won't help someone who submitted a question two years ago and now tries sending an email to that address; but it will save you the time thinking up new, sufficiently abstract email addresses each time you've got to rotate one out.