UPDATE PENDING MAIL

Fires when there is pending mail.
 UPDATE_PENDING_MAIL
==Payload==
None
==Details==
* Fired when the player enters the world and enters/leaves an instance, if there is mail in the player's mailbox.
* Fired when new mail is received.
* Fired when mailbox window is closed if the number of mail items in the inbox changed (I.E. you deleted mail)
* Does not appear to trigger when auction outbid mail is received... may not in other cases as well