Add custom domain email requirements to B2B invitation email docs#1994
Add custom domain email requirements to B2B invitation email docs#1994jconley76 wants to merge 2 commits into
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Add prerequisites section covering mail-enabled tenant requirements, MOERA domain guidance, and DNS configuration (SPF, DKIM, DMARC) for custom domain invitation emails. Includes guidance for both Exchange Online and third-party gateway scenarios. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jconley76 : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change. |
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Learn Build status updates of commit eb07872: ✅ Validation status: passed
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Can you review the proposed changes? IMPORTANT: When the changes are ready for publication, adding a #label:"aq-pr-triaged" |
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Pull request overview
Adds guidance to the B2B invitation email documentation to help customers successfully send invitation emails from custom domains by clarifying tenant prerequisites and DNS-based email authentication requirements, including considerations for third-party mail gateways.
Changes:
- Adds a new Custom domain email requirements section after From address.
- Documents Exchange Online mail-enablement requirements and discourages MOERA (
.onmicrosoft.com) usage. - Provides split guidance for SPF/DKIM/DMARC depending on whether outbound mail routes via Exchange Online or a third-party gateway, plus related links.
| ### Custom domain email requirements | ||
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| When invitation emails are sent from your organization's custom domain (rather than the default MOERA domain), the following requirements must be met for successful delivery. |
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| #### Mail-enabled tenant | ||
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| Your tenant must be mail-enabled with an Exchange Online (EXO) license. Without this, invitation emails can't be sent from a custom domain. If your tenant doesn't meet this requirement, invitations are sent from `microsoft.com` instead. |
| - MOERA domains are subject to [throttling limits](https://techcommunity.microsoft.com/blog/exchange/limiting-onmicrosoft-domain-usage-for-sending-emails/4292065). | ||
| - Emails sent from MOERA domains have a high likelihood of being filtered as spam. | ||
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| [Set a verified custom domain as the default domain for your tenant](/microsoft-365/admin/setup/add-domain). |
csmulligan
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Hi @jconley76 I've added a few suggestions. Could you also take a look at the AI reviews? Please let me know if you have any questions.
Thanks.
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| If you don't configure any of these settings, the language defaults to English (US). | ||
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| ## Next steps |
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| ## Related content | |
| - [Add a custom domain to Microsoft 365](/microsoft-365/admin/setup/add-domain) | |
| - [Set up email authentication (SPF, DKIM, DMARC)](/defender-office-365/email-authentication-about) | |
| - [Limiting onmicrosoft domain usage for sending emails](https://techcommunity.microsoft.com/blog/exchange/limiting-onmicrosoft-domain-usage-for-sending-emails/4292065) |
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@jconley76 Can you respond to the requested changes or let us know if you would like us to commit them?
@csmulligan - When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.
#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team
| If you don't configure any of these settings, the language defaults to English (US). | ||
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| ## Next steps | ||
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| > [!IMPORTANT] | ||
| > If your organization doesn't send outbound email directly from Exchange Online, do **not** add Microsoft 365 SPF/DKIM records to your DNS. Instead, align your DNS authentication records with the third-party service that handles your outbound mail. | ||
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| #### Related resources |
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Hi @jconley76 could you please add this section to the end of the article? I’ve included a suggestion on line 114 for your review.
| ms.topic: concept-article | ||
| ms.date: 12/05/2025 | ||
| ms.collection: M365-identity-device-management | ||
| ms.custom: it-pro, seo-july-2024, sfi-image-nochange |
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| ms.custom: it-pro, seo-july-2024, sfi-image-nochange | |
| ai-usage: ai-assisted |
…nce, move section, reformat related content Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Learn Build status updates of commit 66f52b1: ✅ Validation status: passed
For more details, please refer to the build report. |
PRMerger Results
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Summary
Adds a Custom domain email requirements section to the B2B invitation email elements page (docs/external-id/invitation-email-elements.md), placed after the From address section.
What's included
Context
This addresses customer-reported B2B email delivery failures where custom domain invitation emails were not being delivered due to missing or misconfigured DNS authentication records. Customers using third-party email gateways were incorrectly told to configure M365 DNS records, which conflicted with their existing email infrastructure.