you send confirmation emails after signing in
Tha way you avoid, in case someone accidetally signed in with a wrong email address, that the twitter name/account is already taken and blocked. Happend to me: had a spelling mistake in my email address, forgot my password and - since I can't receive the new passform email - now can't login anymore nor sign up for my own accout under the real email address... :(
so, approval message and something like that can't happen.
We’ll look into further ways to resolve matters involving misspelled email addresses.
To much hussle