The MSG system is a means of sending a brief missive to an invididual. If they are currently not in Avalon, they will receive notification of your message upon their next re-entry. Messages are permanent, subject to deletion.
Another, more terse, form of communication is via the MSG system. This will allow you to send brief messages (at the cost of five gold pieces each; first message each time period is free of charge) to unavailable players, MSG <player> <text> being the syntax. The intended player will be notified of any unread messages upon his next play of Avalon and can read them at any time using the command RMSG. These short messages are stored indefinitely for your perusal, although you may find it necessary to CMSG (clear your messages) every once in a while, to avoid getting bogged down with ones you have already read. This brief messaging system also has the function of informing you of any significant changes to your character that have taken place while you have been absent. For example, someone may have declared you an enemy of their township, or some deity may have given you their favour.
As you grow more experienced in the land your senses will hone and you will pick up some occurrences pertinent to your character or your city/guild even when you are not in the land. This will result in you being notified via your messages, so when you RMSG next time you enter the land, the notification will be shown along with any other messages. Sometimes, particularly after long periods of absence, you will find hundreds of messages documenting your character development in-absentia when you return - and thus find it difficult to pick out the personal notes from friends. To sort the wheat from the chaff you have the PRMSG command. It works precisely like RMSG except it only shows personal commmunication from your fellow Avalonians - leaving out everything else.