Mark Cuban -- I've BURIED THE HATCHET with Jason Kidd

The nasty feud between Mark Cuban and Jason Kidd is officially OVER ... at least for now ... 'cause Mark tells TMZ the two have made up -- and have even started emailing each other again.

Cuban famously TRASHED Kidd in the media last year after Jason decided not to re-sign with Cuban's Dallas Mavericks ... and instead struck a deal with the NY Knicks.

Cuban had said he was "more than upset" with Kidd -- and said there was "no chance" he'd ever honor Jason by retiring his Mavs jersey.

But something happened over the last few months ... 'cause when we asked Mark how he felt about Jason landing the Brooklyn Nets head coaching job this week, M.C. told us:

"I'm excited for him. He has great knowledge on the game so I'm sure he will do well. And yes we have started emailing again so all is well with the world.”