Post Office IM
An urgent instant message that takes so long to be responded to that it would be more time efficient to send a response through the post office. More often than not this occurs when the receiving party is actively participating in another activity.
Post Office IM Conversation:
Sender: Hey can you pick me up in the morning and take me to work?
... (30 minutes later) ...
Receiver: Sure!
Sender: Hey can you pick me up in the morning and take me to work?
... (30 minutes later) ...
Receiver: Sure!