$ ls topics/exchange/

Exchange

2 articles.

Jul 21, 2026Shield11 min read
The evolution of Shield's mail flow architecture
Three versions of Shield's mail flow architecture, from a blunt MX record to a design that hands the last mile back to Microsoft, and what changed each time along the way.
Christian Maddox·Senior Software Engineer
Jun 30, 2026Postmortem10 min read
How Microsoft 365 decides which tenant email belongs to
A new mail-flow rollout made Microsoft 365 attribute every customer's mail to our tenant. The undocumented rule behind it, and the fix.
Mailprotector·Engineering Team

The evolution of Shield's mail flow architecture