As philrob says, but there is another way, rather than miss the mash out you can combine it with the batch sparge.
Use hot enough sparge water (usually acidified) to heat the batch sparge to nearly 80oC. This gives the benefits of the mash out (better extraction, increased fluidity of the wort...).
There is one other benefit, the wort that was run off to the kettle will still have enzyme activity going on, so any unconverted starch that was washed into the kettle will get converted. As the relatively large amount in the kettle will only be raised a couple of degrees when you add the sparge, the enzymes will continue to work until you start applying heat, at least until you heat the whole kettle full up to the high 70oC's.
Sort of like the process used in a lot of English breweries up until around the 1950's when better temperature control and automation started making continuous sparging much more economical.
The temperature of your sparge water needed to hit say 79oC in the batch sparge can be calculated fairly accurately, might be worth having a play around with.
Mark