Can't Mail Gold or Items to Another Realm or Faction

Characters can send mail to each other as long as they are on Connected Realms.

To send items between realms, you must include the realm name along with the character name using this format: CharacterName-RealmName

Modern World of Warcraft

• You can send Battle.net Account Bound items to your own characters on any realm
• You can send gold and non-soulbound items to your own characters on the same realm, even if they are of the opposing faction

Note: While you can trade gold and non-soulbound items with characters of the same faction on any realm, it cannot be done using in-game mails.

Cataclysm Classic

• You can send Battle.net Account Bound items which can be mailed between characters on different realms or factions.
• You cannot send gold or items between factions.

Classic Era

In World of Warcraft Classic, nothing can be mailed between factions or realms.