[German]Microsoft is not having a good run at the moment – yesterday (April 9, 2025) the Exchange Admin Center was down worldwide for a few hours. Microsoft then rolled out a fix and everything seemed fine again. Today, I'm receiving reader reports that users no longer have "send as" authorization for shared mailboxes, which means they can no longer send mails.
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EX1051697: Exchange Admin Center down
I had pointed out the Exchange Admin Center (EAC) issue on April 9, 2025, see my German blog post EX1051697: Exchange Admin Center (EAC) weltweit gestört (9. April 2025).
Administrators around the world were no longer able to access the service as these accesses were rejected with an HTTP Error 500. The problem is documented by Microsoft under EX1051697 in the Service Health section of the M365 Admin Center and, as far as I know, has been resolved.
"Send as" on shared mailbox broken
This morning, April 10, 2025, German blog reader Fermi wrote in this comment that "of course the next problem arose today". A number of his customers can no longer send on behalf of a shared mailbox (send as), even though they have the necessary rights. The reader was personally affected by the company's support mailbox.
Another user got in touch and confirmed the blog reader's observation. Affected users receive the following error message:
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"Diese Nachricht konnte nicht gesendet werden. Sie besitzen nicht die Berechtigung, die Nachricht im Auftrag des angegebenen Benutzers zu senden."
"This message could not be sent. You do not have permission to send the message on behalf of the specified user."
Parallel to the above comments, blog reader Christian R. contacted us by email and confirmed that he was also briefly affected by the Exchange Admin Center problems yesterday. He also writes that, interestingly, since "this morning" they have been unable to use the "Send As" permission on a shared mailbox.
The emails come back with an error message saying that you don't have the authorization to send "On behalf of". He wrote: "Sure, because I want to use Send as and not on behalf of." He thinks that there are probably other "crunches" in the Exchange Online area.
Anyone else affected by this problem? Is there a solution or information from Microsoft?
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