Here is another question from stackexchange.com.
"In a downspout joint, should the female pipe always be down and the male up?
I have recently installed my first downspout and I think I did it wrong by inserting the bottom pipe into the top one, i.e. put the male on the bottom, because now it leaks through the crack in the joint and the wall of the house get really wet. I was thinking to put sealant in but, since it's not too hard to do, I will just replace the whole downspout and put the bottom in the joint over the pipe above it (male on top, female on bottom). That way, all the water will be channeled down the downspout and there should be no leaks."
Downspouts should fit together just the opposite as stated above; The male side points down and the female points up. This law applies to straight lengths of downspouts as well as elbows.
In the photo example above A feeds into B which feeds into C then fits into D. Usually one end of each downspout is tapered slightly on one end, so that it can feed into another downspout.
Downspouts are never sealed together with caulking because they are not under pressure like indoor plumbing. From the gutters to the downspouts, gravity takes care of the whole system.