Mailmeteor - Send hundreds of personalized emails with Gmail.
CleanMyMails - CleanMyMails will clean your mailing list and increase deliverability rate up to 99%.
Mailazy - Modern Email Delivery API
Bouncebuster by Overloop - Bouncebuster is a real-time email verifier that helps you fight bounce & increase email deliverability.
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
Free Email Verifier - The first free and accurate email verification service