some actions taken while account was offline in Lion

"Some actions taken while the account ... was offline could not be completed online." I have seen this message mentioned in Leopard and Snow Leopard. I never got it in that. I am getting it since Lion 10.7.4. About accounts that appeared to be online at the time. Moreover, there are messages that were sent, in that they show up in Sent mailbox, and in at least one case today I got a reply back, but here they are in the Recovered mailbox. So were they sent or not? Can I believe my Sent box or not? And what "actions" were "undone ... on some messages"? There is no list of that anywhere that I can see.