ISP Filtering Logic Variations

Why does your mail land in the "inbox" at Gmail but "spam" at Outlook? This section explains how every mailbox provider's filter is different. Gmail loves engagement, while Microsoft (Outlook) is very sensitive to user complaints.

21 questions in this topic

How does Gmail filter emails? How does Outlook/Hotmail filtering differ? What is Outlook's Focused Inbox? How does Outlook decide if an email goes to Focused or Other? How does Outlook's Junk Email filter work? Can I influence placement in the Focused Inbox? How does Yahoo Mail filter messages? How does Yahoo Mail's spam filtering work? What is Yahoo's Complaint Feedback Loop (CFL)? How are spam complaints handled by Yahoo/AOL? Are there specific requirements for sending to Yahoo/AOL? How do smaller regional providers filter? What’s the difference between MTA-level and inbox-level filtering? How do ISPs build sender reputation databases? What signals do Gmail and Yahoo share publicly (Postmaster, FBL)?; How does Gmail’s “engagement-based filtering” work? How can Gmail promotions tab affect deliverability? What is “smart foldering” vs “spam foldering”? How do providers test new filter rules? How often do ISPs update their models? What is a “probation period” for new senders?

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