When you create multiple lists to segment your contacts, a single contact can be added to as many lists as you want. If you send an email to several lists and a contact appears on more than one of them, we automatically prevent them from receiving duplicate copies of your email. We also have safeguards in place to prevent you from adding duplicate email addresses to your account when you add or import contacts.
Even with processes in place, it's still possible that a contact could receive multiple copies of an email. Here are a few possible causes, along with how you can fix them:
We define a contact based on their email address and not their name. If the same person has signed up for your list multiple times with different email addresses (leigh.grammer@gmail.com, lgrammer@outlook.com, etc.), they are treated as separate contacts. If you send an email to a list, or multiple lists, that include the different email address variations, a copy of your email is received at each address.
To prevent the email from going out more than once through the same send, remove the duplicate contacts from your list. You can delete the extra contact or merge the information together.
After you send an email to a list, you always have the option to copy the email to send it again. If you send the copy to a new list, and you have a contact that is part of your new list and your original list, they will receive two copies of the emails.
To prevent this from happening, use the Resend feature to send an email to the new list. If a contact received the first email and are also a part of your new list, they won't receive the email a second time.
You can create your own A/B test to see how just about anything in your email performs with your audience and use the results to increase your open rate. If you send an email to your "A" list and then copy it and send it to your "B" list, duplicate emails would be sent to a contact who is on both lists.
To prevent the duplicate email from going out, compare both contact lists and remove the duplicate contacts from one of the lists before performing your A/B test.
 | Did you know? When you use our Subject Line A/B Test feature, your A list and B list never receive the same email, and a contact never appears on both lists. |
If your contact has multiple email addresses and sets up emails to automatically forward from one address to another, they'll see the email in both email accounts if you send to the address with the forwarding enabled.
If your contact isn't sure if they have forwarding enabled, have them look at the footer of each email or have them send both emails to you. The email address that you originally sent the email to is included in the footer at the bottom of the email and doesn't change when the email is forwarded. Once your contact knows which account to check, they can then disable the forwarding feature.
More often than not, the contact's server or firewall is the reason they're receiving duplicate emails. Unfortunately when this is the case, there is nothing that you as the sender can do, but we can further investigate for you.
 | Important: Before contacting Support, you'll need to obtain the message header for each of the problematic emails. Message headers let us see any patterns or error messages that may shed some light on the root cause of the problem. Click here for instructions. |
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