our Office365 account is working fine since years.
We have public folders to receive mails to addresses like *** Email address is removed for privacy ***".
Some time ago there were issues, we needed to adjust rights and then it worked fine again.
Until now - since some day in June the public folders do not accept mails from the outside any longer (e.g. from Gmail or GMX).
The sender gets a "Mail delivery failed: returning message to sender" error, with that message:
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of
its recipients. This is a permanent error. The following address(es)
*** Email address is removed for privacy ***:
SMTP error from remote server for RCPT TO command, host: xxxxxxxmail.protection.outlook.com (220.127.116.119) reason: 550 5.4.1 [*** Email address is removed for privacy ***]: Recipient address rejected: Access denied
No clue. Could someone help, please?