BounceProof screens known spamtraps before SMTP checks

Commit: 49ee78d · Date: 15 August 2026

BounceProof adds verification/spamtraps.py, configurable CSV discovery, lowercase normalization, thread-safe caching, and a packaged list of approximately 1.2 million known trap addresses. The verification engine checks the list before disposable-domain and SMTP processing. Matches return risky, reason spamtrap, and safe_to_send: false; SMTP is not attempted.

Regression tests cover case-insensitive lookup, trap classification, and the normal non-trap path.

Why users benefit

Known honeypots become explicit exclusion signals instead of addresses that might be contacted. This can reduce sender-reputation damage, provider scrutiny, and misleading campaign results.

How this increases service value

BounceProof now answers a more valuable question than “does this mailbox respond?” It helps determine whether an address is prudent to send to, strengthening the service’s deliverability-safety promise.