Email is a funny medium.
Boards seems to be closely related to text messages and IMs, it's an instant thing, or seemingly so. Short blips, to the point, over and over again .. a virtual conversation. Some people see email, especially long emails as just too damned much, so you probably won't always get the responce you're hoping for.
Hell, i work from home, and check my email every 3 minutes. unless you catch me when i'm sleeping you'll probably get a responce within an hour at the most on weekdays. I have friends that check their email once a week at best. so it's different to everyone.
and really i think once you hit 20, no one gives a damn about how old you are. it's not like you're 70 and sending an email to a 12 year old about his neopets account. information is information, i personally don't care how old the person is it comes from.
Now if you opened the email with ... "young sweet sweet boy, SWM in search of no strings attached help with dellorto carb" i think you're safe.