Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Yesmail - Yesmail provides email marketing solutions that integrate mobile, web, and social channels for marketers.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
MailPlus - MailPlus is a Dutch-based email marketing solution provider.
DeBounce - Email Validation, Email Checker, Data Enrichment and Appending Tool. Using DeBounce remove invalid, disposable, spam-trap, syntax and deactivated emails.