Cite as: Real Problem AI problem “Why does Outlook send my self-hosted email to spam and then ban my server's IP?”. Opportunity score 7.0 out of 10 (severity 7, AI feasibility 7, market signal 7, competition gap 7). Category Others. Trend Agents. Source signal: Ask HN "How do people self host email and maintain deliverability?", 24 October 2026.. Canonical URL: https://www.realproblem.ai/idea/why-does-outlook-send-my-self-hosted-email-to-spam-and-ban-my-server-ip.
Why does Outlook send my self-hosted email to spam and then ban my server's IP?
People who self-host email set up SPF, DKIM, DMARC and reverse DNS correctly and still land in Outlook spam, then get the IP banned with no reason given and no way to appeal.
Who has it: Developers and small businesses running their own mail server on a VPS, and the sysadmins who look after them.
- Severity7/10
- Feasible today7/10
- Market signal7/10
- Competition gap7/10
Heard in public
“I sent 3 emails to my personal outlook/hotmail accounts, all of which went to spam. 1 day later, my IP was banned.”
Quoted word for word from the public post linked below. Nobody submitted it to Real Problem AI.
Ask HN "How do people self host email and maintain deliverability?", 24 October 2026.What nothing does yet
A deliverability doctor for self-hosted mail that checks the VPS range's history, warms the IP with real traffic, reads Outlook and Gmail bounce codes, and walks you through the exact Microsoft delist form with the evidence it asks for.
Tools that solve this
3 named so far, and where each one stops.
- Microsoft SNDS and JMRP
Shows some IP reputation data, but not why a block happened or how to lift it.
- mail-tester and MXToolbox
Check DNS records and blocklists, but pass setups that Outlook still rejects.
- SMTP relays (Amazon SES, Postmark)
Fix deliverability by routing mail through their IPs, giving up the self-hosting the user wanted.
How you might build it
- 01DNS and blocklist checks
- 02IP range reputation data
- 03Bounce code parser
- 04Warm-up scheduler
- 05LLM guided delisting
#NOV63 · Canonical URL: https://www.realproblem.ai/idea/why-does-outlook-send-my-self-hosted-email-to-spam-and-ban-my-server-ip