The struggle between ISPs and spammers became so fierce, that the ISP side had to evolve beyond simple measures for keeping spam out. ISPs now have an array of technologies to help them determine if a sender is legitimate or a spammer. One of these techniques are spamtraps and honeypots.
What is a Spam Trap?
By definition, a spam trap is an email address maintained by an ISP or third party, which neither clicks nor opens emails, so it does NOT actively uses emails.
There are two kinds of spam traps:
Scraper-traps or honey pots, which are email addresses created and spread across websites, forums etc. waiting to be scraped or harvested by spammers. Some organizations involved in fighting spam put specific email addresses on a website for the sole purpose of attracting spammers to use harvesting software to gather and send spam emails to.
The other popular trick is to use recycled email addresses, which are email addresses that once belonged to a user, but have since been abandoned or closed. ISPs reactivate these adresses at a later date and monitor to see who is still emailing to that address.
The sole purpose of spam traps is to determine if you are marketing to recipients who have opted in to receive your emails, remove / suppress bounced emails and are mailing to recipients who engage with your emails.