Hello Nancy,
I'll mention one that probably no one else will: Email Verify.
Close enough to my own suggestion ! :-) But I didn't knowit was possible to verify e-mail validity beyond purely syntactic verification.
It checks to see if they enter a validand reachableemail address. It has no visible component, so it may not even be on your radar, but I consider it indispensable in the war against spam.
It is for sure helpful !
Could you provide pointers ?
Thanks much ! Sherab.