Email verification can really improve email deliverability. Success of any email marketing program largely depends on its email deliverability. No longer get fake email addresses & hard bounces. You can verify email addresses when editing records and even do bulk verifications from the list view.
donkennedy
gave this add-on 
stars.
Review:
Excellent plugin with extremely fast and competent support. Can't believe we've lived without this plugin for so long. It is so simple, quick and easy to use that everyone who cares about maintaining a clean email list and reputable email sending domain should have this.
