Setting up dual email routing with Google Workspace and Mailgun

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1

Hey folks, I’m trying to get split email delivery working between Google Workspace (formerly Google Apps) and Mailgun. I’ve looked at some old posts about this but couldn’t find a clear solution. Every time I test it out, I keep getting this error:

The error that the other server returned was:
550 5.7.1 Relaying denied

I’m not sure what I’m doing wrong here. Has anyone successfully set up this kind of dual routing system? What steps did you take to make it work? I’d really appreciate any tips or tricks you can share. Maybe there’s something obvious I’m missing in the configuration?

Thanks in advance for any help you can offer!

2

I’ve dealt with this exact issue before. The key is ensuring proper authorization between your servers. Double-check your SPF records - they’re crucial for preventing that 550 error. Also, verify that Mailgun’s sending IPs are whitelisted in your Google Workspace settings. It’s easy to overlook, but can cause major headaches. One thing that helped me was setting up a catch-all address in Mailgun to troubleshoot routing issues. Don’t forget to test thoroughly with both incoming and outgoing messages once you’ve made changes. It took some trial and error, but I eventually got it working smoothly.

3

hey there excitedgamer85, i’ve had similar issues b4. make sure ur MX records are set up correctly for both google workspace and mailgun. also, check if u need to verify ur domain with mailgun. sometimes that 550 error means the sending server isnt authorized. hope this helps!

4

I’ve been down this road before, and it can be tricky. One thing that’s often overlooked is the DKIM setup. Make sure you’ve properly configured DKIM for both Google Workspace and Mailgun. This helps with email authentication and can prevent relaying issues.

Another aspect to consider is your Mailgun routes. Ensure they’re configured correctly to handle the specific email addresses or domains you want to route through Mailgun. Sometimes, a misconfiguration here can cause unexpected behavior.

Also, don’t forget to check your Google Workspace mail routing settings. You might need to set up split delivery there, specifying which addresses should be routed to Mailgun.

Lastly, patience is key. These setups can take time to propagate fully. If you’ve made changes, wait a bit before testing again. It’s frustrating, but sometimes that’s all it takes.