术语表
什么是 Soft bounce
定义
A soft bounce is a temporary delivery failure: a full mailbox, an unreachable recipient server, or greylisting. The address is still valid, and delivery is usually retried on a back-off schedule over a few hours or days.
Soft bounces do not require removing the address immediately, but a sustained rise signals reputation trouble. After many consecutive soft bounces, an address is usually treated as inactive.