Friends and letters
The friend list, invisible mode, the group chat room and the internal mail that works with the recipient offline.
Updated on August 10, 2026MU has three contact tools outside of public chat: the friend list, which shows who is online, the chat room for talking to several people at once, and internal mail, which delivers a message to someone who is not even in the game. All three belong to the server, not the client, so they work between any pair of characters.
- 1,000zen per letter sent
- 50letters in the mailbox
- Ffriend list key
Friend list
Adding someone means sending a request. It only becomes a friendship when the other person accepts, and then the link is stored on both sides. Removing also deletes it on both: there is no one way friendship.
- 1You send the request
By typing the character's name.
- 2The other person receives it
Right away if they are online; on their next login if they are not.
- 3They accepted
You show up on each other's list, with the online state.
- The server sets no limit on friends. The real cap comes from the protocol and the client interface.
- When you log in, the list arrives all marked as offline and each person's real state shows up shortly after.
- There is an invisible mode: you keep playing and show up as offline to your friends.
Chat room
From the friend list you open a chat room with one of them and invite more people in. It is the channel for organizing an event or coordinating farming without cluttering the map chat.
| Rule | Detail |
|---|---|
| To open the room | both need to be online and actually friends |
| To invite someone else | they have to be your friend and not offline or invisible |
| Participant limit | the server checks none; the cap is the client interface's |
| When the room closes | as soon as it is empty |
Internal mail
A letter is the only way to leave a message for someone who is not online. It stores the date, the sender, the subject, the text and even the appearance of the character who sent it, which is the figure shown when you open the message.
| Rule | Value |
|---|---|
| Cost per letter | 1,000 zen |
| Mailbox capacity | 50 letters |
| Minimum level to send | none |
| Need to be friends with the recipient | no |
| Recipient offline | receives it on their next login |
| Recipient online | receives it right away |
- The server first checks that you have the 1,000 zen.
- Then it checks that a character with that name exists. If it does not, the letter is refused.
- The zen is only taken after the letter is successfully stored.
Where everything lives
| What | How to open it |
|---|---|
| Friend list and chat room | key F |
| Mailbox | through the same friends window |
| Party chat | the ~ prefix on your message |
| Guild chat | the @ prefix |
| Alliance chat | the @@ prefix |
| Whisper to a player | through the chat's recipient field |