You're trying to make sure a connector that you want to create will work properly.
You've run the validation check, but something is wrong.
The real question is: For any user, sending an email is a very simple process.
When you send mail to someone (say to [email protected]), your mail typically goes from your E-mail client to an SMTP server.
On this site, comments are invited via e-mail then there are no problem with the verification of the e-mail address of the visitors since I have received the e-mail. In this case, visitors can post comments directly and the lowest level of identification required from the visitor is a valid (and if possible verifiable) e-mail address.
This prompted me to search ways of validating/verifying their e-mail address before their post hits the blog.
An IP address with the poor reputation may get blacklisted by popular email services like Gmail, Hotmail, AOL & Yahoo.