The !msg command allows you to leave a message for a friend. If your friend is not currently a user on the bot, the bot will send a short greeting before it sends your message. With this command especially, it is important to remove spaces from the username to send to, and you can use an ICQ UIN as the username to send to someone on icq.
Syntax: !msg username message
OvEn ToAsT (3:43:47 PM): !msg oventoast hi
toasts aim bot 0 (3:43:50 PM): message left for oventoast
toasts aim bot 0 (3:43:51 PM): oventoast: [Aug 9 22:43 UTC] hi