I've been happily emailing someone, but now can't send any emails.

Am I the only one?

I can send mail to other people, but not the person I've been chatting to! Is there a limit to how many messages you can send someone?

I am not a specialist, but not that I would know! It probably happens if the other person has blocked you (maybe accidently?) If that might help...

And I thought we were getting on so well!!

But see it as more likely that the flirtbox site just had again some problems to run smoothly, I meant only to point out, that she blocked you is one option, so give it another try