How to Get Emails Delivered to Microsoft & AOL | How ISPs Filter
Emails delivered to Microsoft & AOL means you are following email deliverability best practices. Deliverability to Outlook.com is based on your reputation. Microsoft releases reputation data via its Smart Network Data Service (SNDS) program. Windows Live Hotmail uses SPF and DKIM authentication. They filter email using Symantec/Brightmail Probe Network, Smartscreen filtering, and other content-level filtering. Blocking may result from being listed with Brightmail; removing those blocks requires contacting Symantec, not Hotmail. The Outlook.com Smart Network Data Service (SNDS) gives you the data you need to understand and improve your reputation. Data includes filtering, complaint rate, and spam trap hits.
What Microsoft Looks for in Email Deliverability Best Practices
They release reputation data via SNDS
DKIM and DMARC authentication
They filter using Symantec/Brightmail Probe Network, Smartscreen filtering, and other proprietary content-level filtering
Listing (If you're listed with Brightmail, Microsoft may block you)
AOL focuses heavily on DKIM authentication and...