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Why did I receive the error "Not delivering to previously bounced address"?

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    It's 5 o'clock somewhere, and your business associate Sir Not-Appearing-In-This-Film calls you in a panicked state saying they never received an email you promised earlier that day.  Being the savvy Mailgun user you are, you look inside your Mailgun Logs (or alternate monitoring method), and you notice his email failed with the message "Not delivering to previously bounced address." 

    So, what does this error mean, and how can Sir Not-Appearing-In-This-Film begin to receive your emails once again?  Don't worry; we'll explain everything you need to know below!


    The problem

    Removing the email address from the Suppressions list of the Mailgun Control Panel will allow delivery of new messages to said address, as long as the address no longer has any issues.


    The cause

    This error indicates that the email address is currently suppressed by our system from further delivery attempts. Why?  Because during a previous delivery attempt to this mailbox, the recipient's email provider returned an error to us indicating that the mailbox/email-address does not exist, or is invalid for some reason.  As such, we suppress the address to protect both your and our sending reputation.  High bounce rates negatively impact sending reputation, which in turn lessens your chances of optimal deliverability significantly.


    The solution

    If the recipient's email address actually exists and any underlying issues with their mailbox have been fully addressed, you can remove the address from the Suppressions list (or via the Bounces API using an HTTP DELETE request). 

    We'll show you how to do this below:

    1. First, log in to the Mailgun Control Panel (if you have not already done so).
    2. Then, within the left-hand navigation pane, click the Send product and then click the Sending option to expand its list of suboptions.
    3. Next, click the Suppressions suboption.
    4. Choose the Bounces suppression type
    5. Check the box next to the specific suppression you would like to delete and then click the Remove selected button on the upper-right portion of the page (alternatively, clicking the Trash icon will accomplish the same result).

    Note: clicking the Remove all button will purge the suppression list.

    Once removed, new messages that you send to the recipient will attempt delivery rather than being suppressed.

    Please note, however, that if there is still an issue with the recipient's mailbox or if the email address is invalid, the delivery will fail and the address will be added to the Suppressions once again.  In such a case, the recipient will need to address the underlying problem concerning the mailbox with their email host so that future delivery can be successful.  Alternatively, if the mailbox simply doesn't exist, do not remove the email address from the Suppressions.

    Finally, to read more about Suppressions, please see this related help article.  


    Need Support?

    Our Support Team here at Sinch Mailgun is happy to help! Reach out to us in the Support section of your Mailgun Control Panel, and we'll be with you shortly!