Maillist cleaning services
https://kb.mailpoet.com/article/287-list-cleaning-services
we strongly suggest that you clean your subscribers’ lists using one of the services below before sending for the first time:
- Kickbox (free up to 100 addresses)
- DataValidation (free up to 500 addresses)
- Proofy
- EmailListVerify
- NeverBounce
- Klemail (France)
- MyEmailVerifier
These services will help you detect emails with invalid syntax and/or can’t be accurately validated. By doing this, you’ll increase the sender reputation, deliverability and conversion rate of your emails by sending them only to real people. However, they won’t find or solve ongoing audience issues, like spam complaints, spam traps, or blacklists. There’s no guarantee your list will be 100% clear.