- If your email is set to go out to more than one list, and you have contacts that may be on more than one of the selected lists, HubSpot will automatically de-duplicate based on the email address.
- Your recipients will only receive one copy of the sent email. You can test this by adding your personal email address to multiple lists (if you are not already a Contact, add yourself under Contacts > All Contacts > New contact), and sending an email to those tests lists.
- This is also true if you use the Send to more feature on the post-send performance page. If you use this feature to add another list after the initial send, you do not need to exclude the list(s) of contacts you already sent the email to, as no contact can receive the same email twice. If a contact is on the original email send list, and is also on the additional list you are sending to, they will not receive the email a second time.