Error: NDR - Unable to Relay (Exclaimer Cloud – Signatures for G-Suite)


You are using Exclaimer Cloud – Signatures for G-Suite, and start to receive bounce-backs from sent messages, stating:

550 5.7.1 Unable to relay. [Response from was 550 5.7.1 g31sm198651edd.33 - gsmtp] (14cc6cfb-d87e-4a2b-be1e-3e4dac63c24f,193811f7-7714-4f41-bb8b-7b4dc2c3cc91)


This issue occurs when the ability to relay through Exclaimer Cloud has failed, and G-Suite is unable to route the email correctly.


Please check the following parts of the Exclaimer Cloud routing setup, to help resolve this issue:

Host Name

  1. Login to the G-Suite Admin page, here.
  2. Navigate to: Apps > G-Suite > Gmail > Advanced Settings.
  3. Select Hosts.
  4. Ensure that the SMTP host listed here, matches the list here:

IP Addresses

  1. Login to the G-Suite Admin page, here.
  2. Go to Apps > G-Suite > Gmail > Advanced Settings
  3. Go to General Settings.
  4. Go to Routing.
  5. Edit the Receive from Exclaimer Cloud SMTP Relay Service.
  6. Under the Authentication header, edit your IP address.
  7. Make sure each IP address mentioned, matches your region IPs here.
  8. Click Save.
  9. Click Save.
  10. Click Save at the bottom of the page:


Haven't found a solution to your problem?

Please click the button below, login to the Exclaimer Cloud portal and raise a support ticket. A member of the Exclaimer Support team will then be in touch.

Raise a support ticket