Outlook deliverability

Microsoft's filters weigh reputation, authentication and content differently from Google's, and they change on their own schedule. A mailbox that lands cleanly in Gmail can be sliding into junk in Outlook the same week, and the send counts will not tell you.

So placement is read per provider. Seed inboxes on Outlook receive test mail from each mailbox and report where it landed, daily, separately from the Gmail reading. The cap for a mailbox is set by the weaker of its readings, because a prospect base always contains both.

Three things move Outlook placement most in our readings: DMARC alignment, a plain-text first message with no tracking, and a bounce rate kept low by sending only to verified or published addresses. The same rules as everywhere, weighted harder.

The proof page shows readings with the file they were read from. Outlook readings for customer programs will be published with the first research post.