Wahadata is email data validation software offers email verification, email address verification, b2b/ b2c email list verify
ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.
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Trumail - Free email verification API
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Proofy - Quickly validate and verify your email lists.
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.