A spam trap is a dormant email account that an ESP uses to catch bad faith email senders. It looks like a real email address, but it doesn’t belong to a real person.

Spam traps can cause your IP address or even your domain to be list denied, affecting your sending reputation and email delivery rates. These spam trap email addresses may have been legitimate at one time, but are now abandoned or invalid.

For example, if one of your contacts got a job at a new company, their old work email address would become invalid. Any contact that hasn't opened or clicked an email from you in over a year could be a spam trap and should therefore be removed from your contact lists.

Types of Spam traps:

Pristine: Pristine spam traps are email addresses that have never been valid and couldn't even opt into receiving email. They are available on public websites but hidden within the site's code.  The purpose of pristine traps is to identify emails who use bad list building practices like scraping websites for emails or purchasing contact lists. They can also be found on purchased or rented lists.

Recycled: Recycled spam traps were once valid email addresses but have since been repurposed by their provider. Someone could have used this address to opt in at one time, but the address has since been abandoned.