- Plesk Obsidian for Linux
After an upgrade to Plesk Obsidian 18.0.23, Send from the specified IP addresses always shows None in Tools & Settings > Mail Service Settings > Outgoing mail mode.
#PPPM-11533 "Plesk no longer “forgets” the IP address selected as the address to send mail from in “Tools & Settings” > “Mail Service Settings” > “Outgoing mail mode”."
- Plesk Obsidian 10 February 2020
If update is not possible for some reason you may try the following
The issue can be safely ignored because Plesk shows None only in GUI but applies changes to Mail server configuration. Mail functionality is not affected.