Microsoft mail flow issues - emails might be bounced back

Microsoft has successfully routed Exchange Online Protection traffic away from affected infrastructure. CodeTwo services remained healthy during the incident. See EX522020 in Microsoft 365/Exchange admin center for more details and RCA.

CodeTwo services are healthy. Microsoft is still working on a fix for Exchange Online. Please follow EX522020 in Microsoft 365/Exchange admin center for more info if your end users are affected.

Microsoft has identified the problem and is currently recovering the services. Here's the information from Microsoft regarding Exchange Online:

Title: Users may be unable to access their Exchange Online mailbox or send/receive messages

User impact: Users may be unable to access their Exchange Online mailboxes or send and receive email messages.

More info: Users may receive an error message including: “550 5.4.1 Recipient address rejected: Access denied” when attempting to send or receive messages.

Current status: Our internal telemetry has indicated that the service has largely recovered. We’re monitoring our systems while continuing our investigation to determine the underlying cause of the issue and whether additional action is required.

Scope of impact: Impact is specific to users who are served through the affected infrastructure in North America, Europe, and the United Kingdom.

Some end-user emails might be bounced back (no matter if they go through CodeTwo or not) due to issues on Microsoft end. Microsoft just reported that the issue is related to M365 services and might impact any M365 users: Users are reporting receiving an error including "550 5.4.1 Recipient address rejected: Access denied" and we are investigating further. More details can be found in the admin center under EX522020. See more here: https://twitter.com/MSFT365Status/status/1630983423694077979. Please contact Microsoft for more information. We will be monitoring the situation as well.