Email verification is very cool feature that linked with email marketing, it helping to find real customers. You can try in on
source.
Callouts or callbacks (aka Sender Address Verification - SAV) are a mould of backscatter. They are reach-me-down aside receiving systems to essay to guarantee that a remote alcohol mailbox exists, during attempting transportation to that mailbox and viewing the response. If badly implemented then they can cause a recantation of mending on a scheme that had its realm forged into the spam. They make use of a RCPT TO sway to study utterance, attempting to replicate what the (over damaged) VRFY control allowed.