+1  A: 

I think you want to use All instead of Any:

dd.Destination.Client.All(c => c.Email != "[email protected]")

eglasius
The other answer works too!
VansFannel
@Vans y, its negating the expression :P - mine reads: all clients doesn't have this email, crhis's reads: there isn't any client that has this email - you can see why they are equivalent :)
eglasius
+1  A: 

Try

var destinations = db.DestinationDetails.
    Where(dd => dd.Language.Lang == "en-US" &&
        !dd.Destination.Client.Any(c => c.Email == "[email protected]"));
chris