Understand spam traps and email blocklists

Email blocklists are lists of IP addresses or domains that have sent emails to spam traps - email addresses used to identify senders who aren't follow email best practices. 

When a recipient server uses a blocklist to filter spam, IP addresses or domains on that blocklist will be identified as spam, and emails from those senders will bounce.

Understand limitations and considerations

• If your free HubSpot account causes HubSpot's shared email servers to be blocklisted, email sending in that account will be suspended and stay locked indefinitely.
• Some blocklists are less impactful than others. The Deliverability Team monitors all reputable blocklists for HubSpot-hosted IP addresses and will reach out if there are any blocklist concerns.
• Since HubSpot only monitors IP addresses, it's recommended to monitor your own domains for blocklistings with free tools like this one. 

Understand spam traps

Spam traps are email addresses used to identify senders who send emails to abandoned email addresses or email addresses never used by a real recipient.

There are three primary types of spam traps: 

• Pristine: pristine spam traps are email addresses that have never been valid. They are available on public websites but hidden within the sites' code. The purpose of pristine spam traps is to identify email marketers who scrape sites for emails or purchase contact 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.
• Typo: typo spam traps contain common misspellings of popular domain names. For example, johnsmith@gmial.com instead of johnsmith@gmail.com. 

Understand how HubSpot responds to blocklisting

The Deliverability Team actively monitors and resolves blocklistings by reputable blocklist operators, such as Spamhaus and Spamcop. If a HubSpot customer sends an email campaign to a list that contains spam traps, HubSpot’s shared email servers may become temporarily blocklisted. 

When a blocklisting event occurs, the Deliverability Team will reach out to the administrator of the blocklist to collect data about the blocklisting event. This data is used to identify the specific email and sender that caused the blocklisting.

Once the email is identified, the Deliverability Team alerts the sender, and the list containing the spam trap is qurantined. The team then ensures the customer takes steps to avoid future listings.

Take preventative steps to avoid blocklisting

Because HubSpot uses shared servers, other senders may be negatively affected by blocklisting. Consequently, sending emails that result in blocklisting violates HubSpot's Acceptable Use Policy and can result in marketing email suspensions, damage to sender reputation, and wide-ranging deliverability issues. 

To avoid sending emails to spam traps and being added to a blocklist: 

• Ensure that you are following email deliverability best practices.
• Clean up your contact lists to ensure you are only emailing contacts who want to hear from you. 
• Turn on the graymail suppression feature to avoid sending to contacts who are unengaged. You can also create your own criteria for unengaged contacts, then exclude those contacts from emails. 
• Run re-engagement campaigns routinely to help maintain a clean and active subscriber list. You can see some examples of re-engagement campaigns on the Community.