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What to do when I get an error message "Code:605 Error:Not delivering to previously bounced address" in SuperOffice Online Service or Marketing?

Updated on 8 May 2025

I am getting a bounce message in my request or mailing statistics after sending a reply to some specific contacts:

Code: 605
Error: "Not delivering to previously bounced address"
Notification: 
headers: [["X-Mailgun-Sid", "WyIyMTVlNiIsICJoYXJyeS5zdW5kZWxpbkBoYW5keW9ubGluZS5uZXQiLCAiZmExZDY2Il0="].....

Why does it happen and how do I fix it?

Most of the customers that use SuperOffice Online solution use out-of-the-box service for sending out e-mails. This service is provided by SuperOffice partner Mailgun.

When some of your recipient e-mail addresses have bounced previously - they are collected in a suppression list. All subsequent e-mail delivery attempts are ignored to protect SuperOffice CRM Online's sending reputation. Bounced e-mail addresses are collected automatically when Mailgun detects events of delivery failures due to permanent recipient's mailbox errors, such as a non-existent mailbox.

However, if you are sure that the recipient's e-mail address is available now there is a way to remove these e-mails from the suppression list. Please forward the e-mail addresses that creates bounce messages to SuperOffice support and request to get them removed from the suppression list. 

 

Note!

  • Soft bounces and other failures (such as ESP rejects an email because it thinks it is spam) are not added to the list.
     
  • If you use your own domain email address we recommend to set up SPF record. Check the articles below for more information:

How to avoid being categorized as spam when sending Mailings from SuperOffice Online?

What is SPF and how do I configure and set it up with Google Account?

 

More information:

Docs: Mailgun - Security and best practices

Article: SMTP errors and reply codes

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