Apr 10, 14:04 CDT
Investigating – Title: Some users may be unable to send outbound email messages in Exchange Online
User impact: Users are unable to send outbound email messages in Exchange Online.
More info: Impact is specific to sending email messages to addresses outside of their organization. Email messages sent other users within the organization aren’t impacted.
Users will see the following within the NDR message: “Remote server returned ‘550 5.7.705 Access denied, tenant has exceeded threshold”
Affected users will encounter this issue in all Exchange Online connection methods.
Current status: Our review of NDRs provided by affected users is leading us to suspect that an anti-spam rule isn’t behaving as expected and contributing to impact. We’re investigating further to confirm this and to identify resolution options.
Scope of impact: Some users attempting to send email messages to users outside of their organization may be impacted.
Next update by: Monday, April 10, 2023, 3:00 PM (8:00 PM UTC)