Microsoft is working to address a widespread service issue affecting the mail flow pipeline for Exchange Online customers across North America and Germany.
The company first acknowledged this incident (tracked under EX1331830) at 10:33 EDT, when it began investigating a stream of reports from users on social media.
Some affected users are seeing temporary SMTP deferral errors, stating "The maximum number of concurrent connections per resource forest has exceeded a limit, closing transmission channel," while others see "Connection was closed abruptly (SuspiciousRemoteServerError)}" messages.
Microsoft said these ongoing issues are affecting Exchange Online users trying to send or access their emails, resulting in extensive delays or failures, and that its engineers are currently reviewing reports to discover the root cause.
"Users are experiencing significant delays in sending and receiving email messages, with some email messages remaining undelivered for over an hour," the company said in an admin center service alert.
