Hello everyone, A while back one of the forum members reached out with an interesting idea related to better handling bad emails in MailWizz. In big lines, the idea is that since we have lots of active MailWizz installs, the owners of these installs could opt-in to send their blacklist info to a central service, of course, anonymously and the email address would be a md5 or sha1 hash (we will call these hashes from now on), so the actual email address is never sent but a hash of it, so no privacy rule is breached. Using certain algorithms, we can detect the grade of a hash, so if a hash comes in from various sources, we can understand if that hash should be marked as a real blacklist or not. Each hash would expire after a certain period of time because as we know, emails can be invalid today but valid tomorrow. So to sum it up, lots of MailWizz installs can opt-in to send their blacklist emails to a central service but as hashes, never the actual email address. This service would then store these hashes for a certain period of time and based on various algorithms would decide if these are bad emails or not. This means we will have a huge database of bad emails in form of hashes which changes continuously. Then same MailWizz installs would have access to this service to check their existing email lists against the stored hashes, thus finding ahead of time emails that should be blacklisted which in theory would help a lot since you'd have access to a huge database of bad email hashes and you can compare them against your subscribers list and see ahead of time bad emails and take actions against them. Now, i don't know the exact specifics of how this will work, i only have a general idea as i shared above and i wanted to post it here to see if it worth exploring and eventually implementing, since of course, this would imply a lot of work but has the potential to actually change things a lot as far as delivery would go. We welcome any ideas / thoughts on this. Best.