I imported about 5000 emails from our CRM and I have about 300 emails that are now listed as blacklisted in Mailwizz automatically. Does this check against some type of database or something? All I did was import them from a CSV file.
There's a local blacklist in Backend > Email Blacklist where MailWizz adds emails in various cases, like when they hard bounce.
When importing, the emails are checked against that database.