Microsoft weights sender reputation via SNDS and JMRP, and rejects unauthenticated bulk mail to consumer Outlook.com addresses.
What transactional email is#
Transactional email is triggered by a user action (receipts, password resets, alerts) and is exempt from most marketing consent rules. Marketing email promotes products and requires consent and unsubscribe links.
Why it matters#
Mixing the two on one domain or stream means a bad campaign can block password resets. Separating them protects critical mail.
Setting up transactional email for Outlook and Microsoft 365#
- Send transactional mail from a dedicated subdomain (for example mail.yourdomain.com) or separate stream.
- Send marketing from a different subdomain (news.yourdomain.com).
- Keep promotional content out of transactional messages to preserve their exemption.
- Apply DMARC to the organizational domain so both subdomains are covered.
How Outlook and Microsoft 365 reports results#
Open a delivered test message in Outlook and Microsoft 365 and view the original or headers. Look for Authentication-Results and any provider-specific verdict headers. Use the provider's sender dashboard for aggregate reputation.
Common mistakes#
- Adding upsell banners to receipts, which reclassifies them as marketing under many laws.
- Using one shared IP pool for both streams.
Frequently asked questions#
Do transactional emails need an unsubscribe link?
Not under CAN-SPAM if purely transactional. Gmail's bulk-sender rules still expect one-click unsubscribe for anything sent at volume, so many senders include it anyway.
Does Outlook and Microsoft 365 require transactional email?
Microsoft weights sender reputation via SNDS and JMRP, and rejects unauthenticated bulk mail to consumer Outlook.com addresses. Treat transactional email as required for any meaningful volume.