Outlook and the junk folder
What to check when your usend email lands in Outlook or Hotmail junk.
Outlook.com, Hotmail and Microsoft 365 use SmartScreen-style filtering that weighs reputation heavily, on top of authentication. delivered in usend means Microsoft accepted the mail, not that it reached the inbox.
Check authentication
Open the message headers and look at the Authentication-Results header for spf=pass, dkim=pass and dmarc=pass. Microsoft has required SPF, DKIM and DMARC alignment from high-volume senders since 2025. See Verify a domain and DMARC.
Common causes
- New domain or sudden volume. Outlook is strict with unknown senders. Start small and grow: Warm up a domain.
- Old or unengaged addresses. Microsoft hotmail addresses abandoned long ago can turn into spam traps. Prune: Audience hygiene.
- Links and images. Many redirects, shorteners and image-only layouts raise the score.
- Corporate tenants. Microsoft 365 organizations add their own rules and allow lists. A message can be fine for consumers and junked at one company; ask the recipient's IT team to allow your domain.
Ask recipients to help
- Mark the message as Not junk and add the sender to Safe senders.
- In a company tenant, an admin can add your domain to an allow list or a mail-flow rule.
Microsoft's tools
Microsoft offers Smart Network Data Services (SNDS) and the Junk Mail Reporting Program to senders who own their IPs. If you send through the platform's shared IPs, usend deals with those on your behalf. If you have dedicated IPs, ask the usend team for the IP addresses to register.
If mail is rejected, not junked
A bounce with a code like 550 5.7.1 or 550 5.7.509 is a policy rejection: usend does not suppress the address for it. Read the bounce message in the event and see Bounces and suppressions.
More: Why emails go to spam.