Mixed conditionals

A so-called mixed conditional is a conditional that does not follow the usual patterns of zero, first, second or third conditional in terms of the time relationship between the clauses.
Real conditionals can have conditions in the past and results in the future. If Mandy got my message, she'll be at the meeting. Situation: There is a meeting this afternoon. It is now midday. You left a message about the meeting for Mandy this morning. You don't know if she received the message, but Mandy always comes to meetings if she knows about them. Someone asks if she is coming to the meeting, so you respond with the mixed conditional above.

If they left at eleven, they'll be here by one. Situation: You are expecting some friends to come to your house for lunch. It takes two hours to get to your house from their house. The time now is between eleven o'clock and one o'clock. Your partner asks when you think they will arrive. S/he says they called just before they left their house at eleven o'clock. You reply with the example above. Unreal conditionals can have conditions in the past and results in the present. If I'd had lunch, I wouldn't be so hungry.
Reality: I didn't have lunch today. It's now late afternoon or evening. I am hungry.