After experiencing a massive outage with Microsoft 365, I'm curious about how other organizations handle email backups. In past outages, emails would queue and eventually get delivered, but this time we lost several hours' worth of emails, which didn't sit well with our team.
We're considering several options, like manually queuing emails through a third-party filter or using an alternative outbound mail tool. However, this still relies on M365 being functional enough to send messages to the third party. Setting up a completely new email environment seems impractical due to its high costs.
For larger companies like mine, which have the budget for a solution, managing expectations for email continuity is challenging. I've found limited information online, and it seems like many organizations are stuck waiting during outages.
So I'm wondering, do any of you have backup systems or processes in place to protect communications during these incidents, or are we all just hoping for the best when M365 goes down?
5 Answers
Not sure why anyone would invest heavily in backup systems. Typically, email will just spool and be delivered once M365 is back online.
One viable option is to set up a second tenant in a different region, configured to hold and forward during outages. It’s cost-effective and gives you a reliable backup without breaking the bank.
We recently switched to Mimecast and opted for their premium protection plan, which includes an O365 continuity feature. During outages, it allows us to access both live and historic emails while ensuring delivery without needing extra hardware. I haven’t had a chance to test it yet, but I’m eager to get it set up soon.
Using services like Mimecast or Proofpoint can really help. They buffer inbound and outbound emails, so we didn't lose any messages during the last outage—just delayed delivery.
For our internal communication, we have a backup that allows users to send and receive emails even if M365 is down. But during the last outage, even our backup service struggled to keep up, so it's a good reminder that no system is completely foolproof.

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