you have an email address in "BOX notifications: return email" (located on the same settings page)
If a letter arrives at this mail, then:
- can be added to an existing process (if there is a process ID in the body of the letter and the setting "Do not parse letters into business processes" is not set) - you have this setting enabled and letters will not be added to the process comments
- can create a new process based on the received letter, if the setting "Disable automatic creation of processes based on letters" is not set
Because you do not need the "Disable automatic creation of processes based on letters" setting, and the sender of the letter is an Employee - then a process is created for this employee with the subject and content of this letter
if the contact-sender of the letter is not an employee, then the letter will also try to turn into a task for setting up the system
http://joxi.ru/DmBljEWuJOMDZA (one of the red fields must be specified).
The current settings are empty - i.e. task will not be created
As a result: according to the current settings, a task is created from a letter when an employee sends a letter to the mail specified in "BOX notifications: return email" and since a letter is created only for a specific user, then only this employee writes to the specified mail