Mule

A "mule" is an account that is created specifically to hold or to transfer game items or credits. Because Anarchy Online only allows the transfer of items and credits between two players that are online at the same time, on the same server, and in close proximity, it is impossible for a player with multiple characters in his account to transfer between his characters. When FunCom launched the free account marketing campaign in 2004, many established players created mule accounts to transfer items and money between their characters.

Mules are also used to store extra items because there is a limit how much stuff can be stored in a characters Bank.

Original Source: AO Wikia by Cajun67