- Plesk Multi Server
- It is impossible to disable WordPress or Let's Encrypt notifications on Plesk Multiserver
- On the Management node in Tools & Settings > Notifications there are no options WordPress application updates (administrator's digest),WordPress application updates (reseller's digest), WordPress application updates (customer's digest), Let's Encrypt certificates auto-renewal failure (customer's digest) and Let's Encrypt certificates auto-renewal success (customer's digest).
This is Plesk Multi Server bug #EXTPMS-1361 which will be fixed in future updates.
There is no workaround at the moment.