I'm looking to use a combination of Mailhandler with either Rules or Notifications. When a volunteer creates a "note" (a node that references another node), I want to notify the author of the referenced node. The use case here is a volunteer helpdesk where a volunteer logs a note on a ticket, and the ticket's author receives an email.
It seems like a custom token to locate the ticket author's email would be useful in either situation. Is that the right approach? If so, are there any code samples of creating a D7 token that does something like this?