During the January 2026 outage, internal mail and sending worked but inbound mail piled up in Mimecast, which could not connect to Exchange.
57signal
169reviewsi
A score out of 100. Negative and mixed reviews take points off, and so does having only a few reviews, so a handful of glowing reviews can’t beat a product many people like.
17% Positive9%74% Negative
What customers love, and what they don’tWhat customers noticed
Customer reviews (169)
Add your reviewShowing 17 reviews mentioning outages Show all
Barracuda gateway got 451 4.3.2 errors from Exchange Online during the outage, the first one lasting more than a minute or two for them.
Solo business owner says Exchange Online outbound mail bounced for seven months, with Microsoft support admitting a backend issue but recycling tickets without continuity.
During an outage the admin could only open a Sev-C ticket and had to phone Unified Support, despite paying millions for Enterprise Agreements.
A very large account's Exchange went offline over a license error and Microsoft took four days to fix a backend bug.
A similar tenant lockout at their company was hell and took Microsoft almost a month to fix.
Reports licences and users vanishing and reappearing, the Defender portal failing to load email results and the admin portal not loading during an outage.
Annoyed that during the outage inbound mail was rejected instead of queued by Exchange Online.
Users lost about two hours of email during the January 2026 Exchange Online outage.
Samsung email app keeps asking for the M365 password every few hours even after re-adding the account, days after the outage was supposedly fixed.
During the March 2025 Canada outage the mailbox opened but incoming mail was not delivered until about 1:40pm EST.
Admin saw Outlook sign-in problems for about 45 minutes while Microsoft's status page showed no issues.
MSP admin sees the M365 admin centre down across multiple clients, with errors and partial screens after login.
During the bug that copied outbound mail to admins, called it a colossal mistake that exposed sensitive internal email.
Says Microsoft 365 works only about ten days a year and tries to move customers to another provider.
Has had more uptime issues and quirks since moving from on-prem Exchange to MS365, and cannot do anything about them.
Reports daily issues with Teams, Exchange Online and Intune and prefers on-prem.
Common questions about Microsoft 365
Is Microsoft 365 worth it?
Of the 132 reviews with a clear verdict, 17% are positive, 9% mixed and 73% negative. The praise mentioned most is great value. The most common complaint is poor support.
What do people like about Microsoft 365?
The praise reviewers mention most: great value (14 reviews), easy to use (9 reviews) and reliable (5 reviews). For example: Used the M365 developer tenant for home-lab learning at about thirty cents a month and found it very valuable.
What are the most common complaints about Microsoft 365?
The complaints reviewers mention most: poor support (32 reviews), outages (13 reviews) and renewal price hike (12 reviews). For example: Helped a client locked out of its tenant for over two weeks and calls Microsoft's recovery process disdainful.
What does the signal score of 57 mean?
It's how well reviewed Microsoft 365 is, out of 100. Negative and mixed reviews take points off, and so does having only a few reviews: a service needs plenty of them, compared with the most-reviewed services here, to reach the high 80s and 90s. It's worked out from reviews only, needs at least 5 of them, and updates as new ones come in.
What are the specs of Microsoft 365?
Category: Email hosting.
Where do these Microsoft 365 reviews come from?
169 are quotes from Reddit, each linked to the original. Customer reviews are checked for spam before they appear. Every review, written here or quoted, is read as positive, mixed or negative.