IP address cannot be deleted in Plesk: IP address 203.0.113.2 cannot be removed because it is used by one or more domains for their mail service IP address

Symptoms

• An a attempt to remove an IP address under Tools & Settings > IP addresses results in the following error:

  IP address 203.0.113.2 cannot be removed because it is used by one or more domains for their mail service IP address.

• Some other IP address is set at Tools & Settings > Mail Server Settings > Outgoing mail mode but it is not the one that is intended to be removed.

Cause

There are still some domains that use the IP address that is intended to be removed.

Resolution

To resolve the issue, please follow these steps:

1. Navigate to Tools & Settings > Mail Server Settings.
2. Set mail service to Send from domain IP addresses:
   
   
3. Return to Tools & Settings > IP Addresses > Remove the intended IP Address.
4. Switch back to Tools & Settings > Mail Server Settings > change it back to the desired IP address.