How do mailbox providers evaluate ESP trust separately from sender trust?

Mailbox providers maintain layered trust models that evaluate ESPs and senders independently:

ESP-level trust reflects the platform's overall sending quality, compliance enforcement, and historical behavior across all customers. Reputable ESPs have earned baseline trust.

Sender-level trust reflects your specific domain and sending patterns within the ESP's infrastructure. Your behavior determines your individual reputation.

New senders on trusted ESPs may benefit from inherited baseline, facing less initial skepticism than senders on unknown platforms.

However, poor individual behavior overcomes any ESP trust benefit. A bad sender on a good platform still faces filtering based on their own signals.

ESP trust is like the reputation of a shipping company. Sender trust is like the reputation of an individual captain. Both matter, and authorities evaluate each layer when your cargo arrives.