When a sender repeatedly sends emails to an email address which was previously a valid address but now is presented as hard bounce, ISPs and blacklist providers set up the sender address a spam trap. This means, if the sender continues to send emails to the invalid adress, the sender will be perceived as ignoring hard bounces and may be reported as spam.
A spam trap appears as a real email address, but it cannot be used for any kind of communication purposes.
Since these addresses cannot opt-in an email list, if a spam trap address makes it on your subscriber email lists, and you send an email to this address, it is fathomed that you're not abusing the rules of permission-based email marketing. In other words, you have "hit a spam trap".
These are email addresses that have never been used by anyone else but ISPs.
Recycled spam traps are significantly old email addresses which are not used by the actual owner anymore.
If somebody subscribes using an email address that contains a typo or a fake email address, you carry the risk of exposing a spam trap email address.
The effect of hitting a spam trap may alter depending on:
The type of spam trap,
How many times you take the bait,
If someone makes the mistake of sending emails to a spam trap:
Sender reputation will decrease
Bounce rate of your sender server will increase
Email deliverability will drop,