Twitter gripe About once a week, Twitter sends me an email saying that so-and-so has invited me to join...

Twitter gripeAbout once a week, Twitter sends me an email saying that so-and-so has invited me to join. But I've already joined. (Follow me at @petersuber.) Twitter gives me no option but to "accept" the invitation and create a new account, delete the message, ban it as spam, or unsubscribe to future messages.Why doesn't it give me the option to tell so-and-so that I'm already in, and that my username is such-and-such? Twitter could automate this communication so that I don't even have to see so-and-so's email address.  If I weren't such a Twitter novice, I'd call this stupid design. But I am a novice and may be overlooking something. So let me ask people with more Twitter wits. What am I missing?(As long as I'm writing: I rarely post directly to Twitter, and rarely read my Twitter stream. But I use a couple of mashups to convert my G+ posts, like this one, to Twitter posts. If you see me on Twitter, you're really seeing truncated versions of my G+ posts. If you want to contact me, don't send me a Twitter message, which I won't see. Send me an email.)#twitter_wtf