Microsoft hasn’t had a good week with their hosted email with two breakdowns of Exchange Online and Outlook.com services. One stopped emails in and out, the other prevented messages from being read.
Both Exchange Online (Microsoft 365 hosted email) and Outlook.com run on the same or very similar systems. Usually a reported problem with one service is happening to both.
These two bugs (sorry ‘issues’) have been fixed however there might be lingering effects.
Overenthusiastic email Defender
The first and more troubling was a bug in their email security system, Microsoft Defender, which checks messages for possible viruses, bad links and other nasties. Microsoft’s name for this was:
“Users having multiple issues related to email flow, links within email messages and the Microsoft Defender portal”
Defender started blocking or quarantining legitimate messages. Per Microsoft:
- Users were unable to receive email that contained URLs from legitimate domains like Google or DropBox.
- Users were unable to access links within emails as they were identified as risky.
- Users may have been blocked from sending emails, if their messages were incorrectly flagged as spam or phishing attempts.
Even ‘good’ messages were delayed because Defender was overwhelmed with bogus bad emails. That meant it took longer than usual for messages to get into or out from mailboxes. Admin log reports on email actions were also delayed.
The problem started in late evening of 9 May 2021 (first notice was midnight UTC on 10 May). Microsoft 365 Admins can see the details in Admin Center | Health | Service Health | History. If necessary search for MO255463.
According to Microsoft, the problem and its consequences have been resolved. Defender is behaving itself again. Wrongly blocked and quarantined messages have been released and incorrectly blocked users have their rights restored.
Admins might want to check their blocked user list to ensure someone hasn’t been restored to normal service. Also check quarantined messages for anything that wasn’t released properly during Microsoft’s fix.
Outlook desktop mail is blank
This is a strange outage in both Exchange Online and Outlook.com We’ve not seen this type of problem before which gets the euphemistic title:
“Issue affecting viewing email content in Outlook”
Outlook desktop users could connect to their mailbox as usual but the email message body was totally blank! Microsoft only talks about “Outlook desktop” so we don’t know if both Windows and Mac desktop programs were affected nor which software versions.
Outlook web access and Outlook mobile apps weren’t affected.
The problem started on 11 May 2021 and was fixed early the next day. Microsoft 365 Admins can see the details in Admin Center | Health | Service Health | History. If necessary search for EX255650
Users have to restart Outlook to make emails display properly, in some cases a second restart is required.
Microsoft will only say that “A recent change to systems that facilitate text display management for content within the Outlook client caused impact.” which tells customers nothing more than they already knew.
They add “We’re performing an extensive review of our coding to understand how the issue occurred and why it was missed during the testing and early deployment cycle.”. That’s an excellent question; doesn’t anyone on the dev team use Outlook desktop apps?
We look forward to seeing a frank and honest “post incident report” on this bug.
Have another mailbox on standby
We’ve said it before and say it again. No matter what type of mailbox you use, always have a backup hosted by a totally different company. If you use Microsoft 365/Outlook.com have a Gmail account in your virtual back-pocket ready to use. Same goes for any other mail host because none of them can be 100% reliable and you always need an alternative way to communicate.