Preventing spammer with a lot of dots in email-address

[Holger]

Hello,

for a forum that I took over I am looking for a possibility to prevent spammers with emailaddresses like this to register:
[email protected]
I would like to limit the use of dots.
No normal user has more than lets say 3 or 4 dots in the address.
And yes, we have anti-spam measurements in place, those do not help.

For an old 3.0.x forum I had the maximum of dots custom programmed into the script. That works well. But now I am wondering if we cannot have an Ext instead for everyone to use.

/H