Contains the private notes that can be attached to messages. "Private" in this context means that the notes are not exported to the outside by way of the mail transport system.
Structure of notes
mail_idinteger
Unique internal identifier of the message.
REFERENCES mail
notetext
Text of the note. It should never be empty, because the application code should delete the row when the text is cleared.
last_changedtimestamp with time zone
The date and time when the note was last modified.
DEFAULT now()