Not a problem.   

It depends on the agency.  Shutterstock takes 4 mp, which is my minimum cutoff when doing crops. 

Following along on this topic, although Shutterstock is far and away my #1 earnings producer, I have better earnings from DT editorial than from SS editorial.  I doubt many people have the same experience, but it is true for me.

And which site really sells editorial photos?
On DT the best-selling editorial photo has 100 downloads, but the next one only 31, and then it goes very steeply down. 4 downloads is pretty good there. There are only 442 editorial images on DT that did sell at least once (out of roughly 4000 accepted).

And how about SS? Do they sell much more?

Is it worth it to upload editorials there? I don't think so. I think it is smarter to upload editorials to sites like Alamy. I only hope that the micros won't kill the market for editorial photos. The only losers will be photographers themselves.

For a very good shot of H. Clinton the photog earned a buck, another good shot of B. Clinton has earned another buck...
Do you really want to go there? It's like selling them rope with which you will be hanged in the end...