Block comments from an email domain

[Montage]

I've been getting heaps of spam comments recently - all for one photo, and all from an email address that's <something>@hotbox.com

Is it possible to block comments from an email domain? I've put hotbox as a banned word in my blacklist, but it hasn't helped. Any ideas?

[Connie]

captcha tried?

[Montage]

captcha tried?

Tried it before, but too many people complained that it said they were robots when they had entered the correct numbers.

Installed it again a day or two ago and already had one person say the same thing.

I might leave it on for a while, but unless the number of false positives improves, I can't see it staying for long.

[Connie]

.htaccess is your friend