correspondence outside of the Match

Hi,

Can people who've been through the Match process advise me on whether it is appropriate and/or advisable vs non-advisable to contact program directors directly outside of the Match, e.g. to email the PD a private correspondence stressing one's interest in the program, attributes etc.
Likewise, it is appropriate/advisable to get one's Attendings to phone or otherwise communicate with programs outside of the Match process?

I realise that this may not be "kosher" but if this is common practice in the cut-throat game of getting into a residency please advise me accordingly so that I play the game on a level footing.