Hello @Pennsylvania Pro-LifeF-365908686 ,
No, reCaptcha and similar systems on sign up forms should normally prevent bot sign ups en masse, however there's nothing that would really stop a human just submitting dud email addresses.
The best advice I can offer in this regard is to turn on Confirm Opt-In for your account. This will make it so any contacts that sign up via a sign up form you have associated with your account will need to click a button in an automated confirmation email they receive. Any contacts that don't will stay in Awaiting Confirmation status until then.
If you only manually import contacts, and don't utilize any of our sign up forms, then the only option would be to manually scrub the file prior to import.
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