As if keeping track of all the online chatter weren't tricky enough, don't forget to check your "other" inbox for Facebook messages.
It's the little known, often overlooked folder where Facebook files messages that aren't quite spam but don't come from your nearest and dearest, either.
Think: Notes about event invitations or messages sent from someone -- maybe that annoying ex-boyfriend -- not among your official Facebook "friends."
It's not that you don't get the notes, you just don't see them unless you click on the faint gray "other" on the messages page.
Users can move a message filed there to the main inbox if they choose.
The "other" inbox has been in the spotlight lately since Facebook began testing pay-for-delivery schemes to get messages around the shadow filing system.
For example, want to reach Facebook founder Mark Zuckerberg's main inbox even if you don't know him? That'll be $100.
Tech blog Mashable reported the delivery fee last week, saying Facebook is testing "extreme price points" to figure out what works best to filter spam.
For lesser-known folks, Facebook is testing a service that would allow users to send messages to the main inbox of non-friends for $1 each.
Seems we're not all as in-demand as Zuckerberg.