Outbound Glossary
Spam trap
An address that exists only to catch senders who did not check their list. One hit can undo months of reputation work.
Spam traps are addresses that no person uses. Some were planted and never published, so any mail to them proves the sender scraped or guessed. Others are real addresses that were abandoned and recycled as traps, which is why an old list is more dangerous than no list.
You cannot detect them by looking, and a verification tool only catches some. The defence is procedural: keep lists fresh, remove anything you have not touched in a year, never buy a list, and never send to an address you cannot explain the origin of.