Send the following on WhatsApp
Continue to ChatMicrosoft-Blacklist: Undelivered Mail Returned to Sender https://www.itsicherheitnews.de/microsoft-blacklist-undelivered-mail-returned-to-sender/
Microsoft-Blacklist: Undelivered Mail Returned to Sender https://www.itsicherheitnews.de/microsoft-blacklist-undelivered-mail-returned-to-sender/