Hello One of my clients got a problem to receive mails from one customer. He sends mails from its system through isis.servercorner.net and the mailserver refuses to accept the mail with a «no such mailbox» answer. But the mailserver should not look for the mailbox but forward to M365. We suspect a wrong mx in the dns of servercorner.net. When we look into the mx of the customer, it looks like: dig mx 4plusarchitektinnen.ch +short 0 4plusarchitektinnen-ch.mail.protection.outlook.com. dig 4plusarchitektinnen-ch.mail.protection.outlook.com +short 104.47.22.10 104.47.22.74 The customer was on a hosting somewhere inside servercorner.net and we suspect there are leftovers. Anybody here from servercorner.net? How to contact? Regards, Urs