Everyone using a Heart sender or any other mailer is always recommended to verify leads before the blast.
Bounce back always cause your SMTP to die within no time.
If you send campaigns with zero bounce leads. Your SMTP will stay longer and your inbox rate will always be on the peak.
We have now an Email Verifier 2021. It is loaded with 22 different methods to verify your leads. A perfect leads checker you should have in your tools list.