Some years ago, people could go to a stablehand and write a message that would be delivered by pigeon. The mobol was laggy and subsequently removed. However, it's been spruced up, partially re-written and re-implemented.
At a stablehand say SEND A MESSAGE
The first line of the message has to be MESSAGE TO NAME
GIve the paper to the pigeon and the pigeon will deliver it.
Note that the pigeon will drop it in your recipient's room, so if they are spamming fast, they may miss the delivery. Also note that this is LS to LS only.