Purchasing a contact list
Pure or pristine spam traps are often found in purchased lists. Pure or pristine spam traps are created with the intention of luring in spammers, which is done by placing an email address online where people or robots harvest them illegitimately. Email addresses that are collected in this way are often shared with other spammers or added to bulk mailing lists that get sold or rented. The best way to counter this is to not purchase email address lists. Instead, you should build you up your email contact list using legitimate collection methods such as sign-up forms or through customer support chats. Most importantly, use verified double opt-in to ensure email address are legitimate.

Not keeping good email contact list hygiene
If there is no process to regularly remove contacts that are no longer engaging with your email campaigns, you run the risk of sending to a recycled spam trap. This means that, even if every email address on your list is gathered with permission, there’s still a risk if there’s no strategy in place to make sure contacts still want to receive the email campaigns that are sent to them. A great way to ensure your email contacts are still active is to check if they are still opening your emails or clicking links inside it. Use the non-openers report to check which email addresses are still actively engaging with your emails. Re-engagement campaigns (often referred to as win-back campaigns) are a way to try and engage inactive subscribers. Any contacts that are not engaging with your emails at all can be removed from your lists manually, or you can create a segment to do it for you.

Forcing subscription
Contacts are more likely to intentionally submit a fake email address if there’s a reward for providing it, but they don’t have the option to not subscribe to marketing communications. For example, if your contacts are trying to get a discount and don't want to be emailed.

Making a typing error
Username typing errors commonly happen when email addresses are collected offline and later manually input into your contact list. It’s also a common occurrence when an email address is entered manually to a contact list over the phone, or given verbally at a point of sale when a customer is spelling it out and the associate misunderstands. Double checking email addresses with customers helps to avoid typos or mistakes. Alternatively, requesting the customer fills out a sign-up form or emails you their contact information directly instead of verbally can prevent accidental miscommunication. Adding verified double opt-in to offline collections can also help ensure that the email addresses collected are spelt correctly.

Collect email contacts using legitimate methods such as surveys, pages, and forms.

Add verified double opt-in to make sure the email addresses are valid.

Add options for contacts to unsubscribe from marketing communications in your forms or pages.

Regularly check the hygiene of your lists using analytics.

Make sure your hard bounce rules are set up correctly to remove unknown users immediately.

Don't purchase email address lists.

Don’t use scrapers to scavenge email addresses from websites.

Avoid verbally gathering email addresses and typos wherever possible.