German SMTP IP range on MS block list

Fixed - Microsoft is now accepting mail from smtp.de.opalstack.com. (19:44 UTC — May 14)

Identified - We’ve identified and corrected the cause of the block, and have passed our findings along to Microsoft with a request to delist the German SMTP address.

We’ll update this post when Microsoft have confirmed that the server is no longer on the block list. (17:51 UTC — May 13)

We’ve received some reports that outlook.com and other Microsoft mail services are blocking smtp.de.opalstack.com.

We’re investigating now and will follow up when we have more info. (23:02 UTC — May 12)