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"Not Delivering to Unsubscribed Address"

You send a ton of email because you sell a lot of goods and services.  However, you notice that one of your best customers, Arthur (King of the Britons), is no longer purchasing anything during your sales promotions. Being a savvy Mailgun user, you look inside your Mailgun Logs (or alternate monitoring method), and you notice Arthur's email failed with the message "Not delivering to unsubscribed address.

What does this error mean, and can Arthur (King of the Britons) still receive emails from you?  Don't worry; we'll explain everything you need to know below!

TL;DR Overview

If the recipient unsubscribed, the rule is that you need to honor their decision of unsubscribing from your emails.  The exception, however, is either if the recipient specifically reaches out to you stating the unsubscribe was made in error or if the recipient later opts-in to receive emails once again. In such cases, the recipient should opt-in once again to your emails, and you may then remove their address from the Mailgun Suppressions list.  Removing the email address from the Suppressions list of the Mailgun control panel will allow delivery of new messages to said address.

The Cause

This error indicates that the email address is currently suppressed by our system from further delivery attempts. Why?  Because at some point, after receiving one of your emails, the recipient decided that she or he no longer wished to receive those emails, and as such, unsubscribed from your mailing list. Due to this, we suppress the address to protect the reputation of your domain, and that of our IPs. Additionally, we do this to comply with international laws and regulations. Sending to recipients who no longer wish to receive emails possibly violates numerous laws and regulations and severely damages your deliverability; this is spammer behavior, after all.

The Solution

The solution depends upon the reason behind the cause: did the recipient intentionally or unintentionally unsubscribe?  In the overwhelming majority of cases (i.e. virtually always), the recipient's unsubscribe is intentional; as such, you really don't want to remove their address from the Suppressions, and you need to stop emailing them any further. (An important point: if the recipient opts-in to receive your emails once again at a later date, their address can be removed from the Suppressions list).  In the overwhelming minority of cases (i.e. virtually never), the recipient's unsubscribe is unintentional; as such, if they reach out to you explicitly stating the unsubscribe was unintentional, the recipient should opt-in once again to your emails while you remove that recipient from the Suppressions.

In the case that removing the address is warranted, you can remove the address from the Suppressions list (or via the Unsubscribes API using an HTTP DELETE request). 

Inside the Mailgun Control Panel (options displayed down the left-hand side on a dark column), use the following instructions:

  1. Click on the Sending option on the left-hand side of your Mailgun dashboard.
  2. Click on the specific domain for which you would like to view the Suppressions.
  3. You will click on the Suppressions option.
  4. Choose the Unsubscribes suppression type and then click Delete button on the right-hand side of the specific suppression you would like to delete.

Simply mark the checkbox next to the recipient and use the delete button to remove the suppression.  Once removed, new messages that you send to the recipient will attempt delivery, rather than being suppressed.

Finally, to read more about Suppressions, please see this related help article.  If you have any questions, please open a Support ticket via the Support option of your Mailgun control panel - our team will be happy to assist!