Based on our record, Email List Verify should be more popular than Unlayer. It has been mentiond 2 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
If you're not getting the right email addresses from ContactOut and it's bouncing back, you could always run the email addresses through something like emaillistverify.com to make sure they're valid before you try to email them. (you should do that always anyway to protect your email deliverability). Source: almost 2 years ago
Emaillistverify.com is the service I use. Source: almost 2 years ago
Before that we had some luck using RazorLight, but we did all email templates in an editor Unlayer, exported the html and made a layout and view files. Source: about 1 year ago
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
MJML - The open source framework for responsive emails
ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.
Stripo - Stripo is an all-in-one email design platform. We enable our clients to build emails of any complexity, including interactive AMP emails, really fast and easy.
Email Verifier - Email verifier app lets you verify email.
BeeFree.io - Bee is MailUp's drag-&-drop editor for responsive design emails.