In an attempt to remove
203.0.113.2IP address in Plesk > Tools & Settings > IP Addresses, the following error is shown and as result, it is not clear where the affected IP address is used:
PLESK_ERROR: The IP address 203.0.113.2 is already used for hosting
This address is not used by any domains or resellers.
203.0.113.2IP address is set in Tools & Settings > Mail Server Settings > Send mail from specific IP.
#PPPM-7984 "Improved a confusing error message. When users try to remove an IP address used by the mail server, Plesk no longer incorrectly notifies that the IP address is used for hosting."
- Plesk Obsidian 20 April 2021
If update is not possible for some reason you may try the following
Go to Tools & Settings > Mail Server Settings > Outgoing mail mode.
Select the Send from domain IP addresses option:
Click on the screenshot below to expand
- Scroll down and press the OK button to apply the changes.