Help me debug and resolve on multi-server setup the error: Uid-mapping cannot be changed if there are already mail users. I noticed the error after adding the last server which runs web, email and database services. There are 2 active mail domains on the server with 1 mailbox each. Under -> server config -> mail tab the "Use Websites Linux uid for mailbox" is unchecked. The same goes for all servers that handle email (Generally all servers have same setting). The error appears on System -> Server confing -> Mail tab on all servers.
