Returns whether a mail can be reported as spam. Returns nil for messages from Game Masters or friends, as well as for messages generated by the game itself (Auction House mail, mails from NPCs, etc).
As with most mail functions, only provides valid information if used while the mail UI is open (between the
See also Complaint functions, Mail functions.
mailID- Index of a mail in the player's inbox (between 1 and
complain- 1 if the mail can be reported as spam; otherwise nil (