If you ever get a message that “You are not allowed to post a comment,” there could one of a couple of reason. The most obvious is that you have been banned. I think those people who are banned, and there’s not many of them, will know they have been banned and why.
The more likely reason is that whatever email address you are using to post comments is malfunctioning (perhaps you have a full mailbox or something) and the server is sending me loads of bounce-back messages (“Unable to deliver this email…”). In this case you either need to clear up the problem with your email address, in which case let me know and I will lift the block on the email, or just start posting using a new, valid email address.
To be clear, if I start getting bounce-back emails (because of the “Notify me when someone posts a comment” emails), I’m going to block that email address. This isn’t a ban, just self-preservation.
Update: Seamole, this means you! Even my email back to you explaining this bounced.