Microsoft 365 outage: why your WooCommerce order emails are not arriving

Updated: Friday 13 November 2026, 12:30 (Athens). Since Thursday afternoon Microsoft 365 has had a serious problem in Exchange Online, the service that holds business email. If your shop runs on WooCommerce and you or your customers use Microsoft 365 (Outlook) email, order emails may be delayed or may have been lost.

The orders themselves are not lost. They are saved in WooCommerce as usual. What does not arrive is the notification.

What happened

• The problem started on Thursday 12 November around 16:17 UTC. Microsoft tracks it as EX1550543 (Exchange Online) and MO1550821 (services that depend on it).
• According to Microsoft, a process on the servers that sets up secure connections gets overwhelmed and the servers stop handling requests. The root cause is not confirmed, and Microsoft says it sees no sign of an attack.
• Mailbox access, mail delivery (delayed), Teams calendar, Copilot and other services are affected.
• There was partial recovery in some regions on Friday morning, but at the time of writing Microsoft has not declared it resolved or given a time for full recovery.

Why order emails are not arriving

It depends on how your shop sends email. There are three cases, and the second one is the serious one.

1. The shop sends from its own server or an email service

This is the case if WordPress sends through the hosting server or a service like Brevo, Mailgun, SendGrid or Amazon SES. The sending server finds Microsoft’s door closed, keeps the message in a queue and retries. Emails are delayed but usually arrive once Microsoft recovers. Most servers keep retrying for a few days before bouncing.

2. The shop sends through Microsoft 365 itself

Many shops send through the company’s Microsoft 365 account, usually with a plugin like WP Mail SMTP and the server smtp.office365.com. Then WordPress cannot even connect to send. WordPress has no queue and does not retry, so the email is lost. Both the confirmation to the customer and the “New order” notification to the shop are lost.

That is why today many customers ask for confirmation of orders that went through fine, and shops don’t know they have orders.

3. The shop sends through Brevo, but the business email is on Microsoft 365

This is the most common setup: WooCommerce sends through Brevo with a sender like [email protected], and that mailbox lives on Microsoft 365. Brevo sends from its own servers, so Microsoft 365 is not needed for the email to leave. It only matters when the recipient is on Microsoft 365.

• Customers on Gmail, Yahoo etc.: the confirmation arrives as usual.
• Customers with business email on Microsoft 365, or Outlook/Hotmail: the confirmation is delayed. Brevo holds it and retries.
• The “New order” notification to the shop goes to info@, which is on Microsoft 365, so it is delayed too.
• Customer replies to the order email go to Microsoft 365 and are delayed on their side.

Brevo does not retry forever, though. If the outage lasts long, some emails will be logged as a soft bounce and never delivered. That is why the Brevo checks in step 4 below are needed once Microsoft recovers.

What to do today

1. Don’t rely on email. Open WordPress → WooCommerce → Orders and check new orders since yesterday afternoon there.
2. Find out which case you are in. In WP Mail SMTP (or your SMTP plugin) look at the “Mailer”. If it says Microsoft 365 / Outlook or server smtp.office365.com, you are in the second case.
3. If you send through Brevo, check it once Microsoft recovers. In Brevo → Transactional → Logs, filter from Thursday afternoon and look for “Soft bounce”, “Deferred” or “Blocked”. In Transactional → Blocked contacts, remove any customers, or the shop’s own address, that appear there. Otherwise Brevo will not send them anything again, including future orders.
4. Resend the emails once Microsoft recovers. In each order, in the “Order actions” box on the right, choose Send order details to customer or Resend new order notification and press the button next to it. If your SMTP plugin keeps an email log, you can resend from there too.
5. Tell your customers. A short note on the home page or social media, e.g. “Because of a Microsoft outage, confirmation emails are delayed. Your orders have been received.”, saves phone calls and duplicate orders.
6. Don’t change settings. Don’t change passwords, DNS or email settings because of the outage. It won’t help and can cause new problems when the service recovers.

So it doesn’t happen again

Order emails should not depend on the office mailbox. A transactional email service (e.g. Brevo, Postmark, Mailgun or Amazon SES), set up properly with SPF, DKIM and DMARC, queues emails and retries when the recipient has a problem. It also keeps a log of every email sent.

There is a second reason to do it now. Microsoft has announced that at the end of December 2026 it will turn off by default sending through smtp.office365.com with a plain username and password (Basic Auth) for existing tenants. Admins will still be able to turn it back on, but shops that send this way risk silently stopping.

Want us to check?

If you don’t know how your shop sends email, or want to move it to a transactional service, send us your site address and we’ll tell you what it needs.

You can follow the recovery on Microsoft’s status page: status.cloud.microsoft.

Sources

• LazyAdmin — Microsoft 365 Outage: Current Status
• Cyber Security News — Massive Microsoft 365 Outage Impacts Exchange Online, Teams, SharePoint, Copilot
• The Washington Post — Microsoft races to address outage affecting users around the world
• NSAO — Microsoft 365 Email Outage Continues Into November 13
• Microsoft Message Center MC786329 — Exchange Online to retire Basic Auth for SMTP AUTH