Gold and items cannot be sent to another realm or faction.
What to do if you are missing mail from the auction house with items, gold, or both.
Items or gold left in the mailbox for too long is deleted
Information on how long it may take for different kinds of mail to be delivered.
Troubleshooting World of Warcraft in-game mail issues.
Phishing scams can take many forms—fake websites, suspicious emails, and threatening in-game whispers are the most common types.
Possible causes and how to fix issues related to sending mail in World of Warcraft
Information on unlooted items and The Postmaster.
Have not received gold or items from a CoD (Cash on Delivery) mail.
Player is unable to loot or retrieve Frigid Timewarped Prism from mail