Deliverability & the inbox
Spam trap
Also known as: honeypot email
An email address mailbox providers and deliverability services create specifically to catch senders with poor list hygiene. Sending to one damages reputation immediately, sending to many can get a domain blacklisted.
Spam traps are email addresses created specifically to catch senders who don't maintain clean lists. Three types: pristine traps (addresses that never belonged to a human, a scraped or guessed list gives them away), recycled traps (addresses that were real accounts but got abandoned and re-purposed as traps after ~12 months of inactivity), and typo traps (gmial.com, yahooo.com, scraped from bad sign-up forms). Hitting one spam trap isn't fatal but signals to mailbox providers that your list hygiene is poor. Hitting many, or hitting the same trap twice, triggers blocklist entries at Spamhaus and other RBLs, which can shut down deliverability across mailbox providers for weeks. Prevention: double opt-in on new subscribers, sunset sequences for 12+ month dormant users, real-time email-verification on signup forms.