If you’ve been trying to comment on a WordPress blog and you’ve come across this message:
You must be logged in to comment with that email address.
It appears to be a problem WordPress hosted sites are having at the moment. There is a thread on WordPress about this, but the WP guys themselves haven’t commented or said they’re working on anything.
Personally I suspect it’s not an error, or a problem of any kind, but instead some anti-spam security they’ve enabled to prevent people from spamming websites with comments using certain email addresses.
Anyhow, if you’ve seen this message today or yesterday, or your website’s visitors have reported not being able to comment, this is why.