What are provider-specific algorithms?

Provider specific algorithms are the unique filtering formulas each mailbox provider uses to evaluate incoming email. While all MBPs consider authentication, reputation, and content, they weight these factors differently and apply proprietary logic that varies significantly.

Gmail heavily emphasizes user engagement and domain reputation. Microsoft's SmartScreen focuses more on content patterns and IP history. Yahoo balances complaint rates with authentication compliance. Apple prioritizes privacy and shows less tolerance for tracking mechanisms.

These algorithmic differences explain why deliverability strategies must be provider aware. A technique that improves Gmail placement might have no effect or even negative impact at Microsoft. Smart senders monitor performance by provider and adjust tactics accordingly rather than applying one size fits all approaches.