What I recommend using is [username]@bitcointalk.org, since the forum does not offer email services it would not be possible to hack/create that email address (although you would be somewhat out of luck if you forgot your password)
In the (unlikely) event of successful DNS poisoning, an attacker might be able to forge an MX record for bitcointalk.org and point it at his own mail server.
It's difficult to estimate the likelihood of such an attack, but I personally would consider that more likely than an attack against a professional mail provider.