# Microsoft bouncing all emails from our self-hosted Discourse site (via Mailgun)

**URL:** https://meta.discourse.org/t/microsoft-bouncing-all-emails-from-our-self-hosted-discourse-site-via-mailgun/371739
**Category:** Support
**Tags:** email
**Created:** [June 26, 2025, 2:12am UTC](https://meta.discourse.org/t/microsoft-bouncing-all-emails-from-our-self-hosted-discourse-site-via-mailgun/371739 "2025-06-26T02:12:38Z")
**Posts on this page:** 1
**Showing post:** 1

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### Author: ![nathank](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/nathank/32/290039_2.png) [@nathank](https://meta.discourse.org/u/nathank)
#### Post date: [June 26, 2025, 2:12am UTC](https://meta.discourse.org/t/microsoft-bouncing-all-emails-from-our-self-hosted-discourse-site-via-mailgun/371739/1 "2025-06-26T02:12:38Z")

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After a couple of users complained, I discovered that since Monday our Discourse instance emails (via Mailgun) no longer seem to be getting through to those on Microsoft email tenants. This includes enterprise and general (e.g. [hotmail.com](http://hotmail.com), [outlook.com](http://outlook.com)).

On testing our deliverability, we didn’t have DMARC set up. This has been fixed, and we have a near perfect deliverability score now on [mail-tester.com](http://mail-tester.com):

 ![This screenshot displays a message authentication report from mail-tester.com showing a perfect score of 10/10 with all tests passed, including SPF, DKIM, DMARC, and server/domain validations. (Captioned by AI)](https://global.discourse-cdn.com/meta/original/4X/6/a/4/6a402461d580519ecac2b556d3bc3a6b51954fad.png)

This is the improvement suggestion:

> Your message does not contain a List-Unsubscribe header

We don’t have any customisations for our email template.

Traffic to Gmail and other services seems fine; it is just Microsoft, and this seems to be continuing 24hrs after the DMARC fix.

Of note, Mailgun has put out this notice about Microsoft and email:

> **[Microsoft Outlook sender requirements 2025: What senders should know -...](https://www.mailgun.com/blog/deliverability/microsoft-sender-requirements/)**
>
> Microsoft will begin filtering non-compliant emails on May 5, 2025. Learn how to meet new Outlook sender requirements and protect your email deliverability.

In summary, if DMARC is set up, we should be fine (but currently are not). While this was meant to kick in on 2025-05-04T12:00:00Z, there is an ominous note that:

> **Later (date TBD):** Expect full rejections for senders who remain non-compliant.

Has anyone else noticed an impact of this with their outgoing emails bouncing? Any suggestions as to how to proceed from here?

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_[View the full topic](https://meta.discourse.org/t/microsoft-bouncing-all-emails-from-our-self-hosted-discourse-site-via-mailgun/371739)._