Hard bounces get blacklisted while soft bounces will not, they get retried 5 times before the app decides they are bad emails and they don't worth retrying anymore, at which point, they get blacklisted too.
ThanksIf your email provider is considering this error as a soft bounce, Mailwizz is processing them accordingly. Mailwizz is retrying depending on the bounce type, not depending on the error message.
Think of soft bounces as blocks that are a short term issue–you don’t need to permanently take these addresses off of your list. However, hard bounces are either invalid or non-existent addresses that should be removed immediately.