I set my youtrack as HelpDesk - according to this link - https://confluence.jetbrains.com/display/YTD6/How-to+Use+YouTrack+as+a+Help+Desk#How-toUseYouTrackasaHelpDesk-partII
All is done.
But if I send email to HelpDesk mail I receive feedback:
A following problem occured while processing email from mailbox:
Failed to apply command " Last message related emails "notifier email" "helpdesk email" to issue created from email from "notifier email"
unknown command: Last message related emails "notifier email" "helpdesk email"
Where I did error?