allow mailing items between chars from same RDF different factions

some time ago i as a warrior tank in a rdf dungeon was ninjaed, so I filed a ticked (with quite detailed who what when + chat conversation) for a ninja and gm replied: "you have to provide screenshot that you signed and entered as a tank" - ...which is a brain-fart because... who makes a ****in screenshot every time he signs-in/enter in a dungeon because he's expecting to be ninjaed in the end?
So i said **** it.
Today, a certain player from alliance, the lowest dps ever and half the dungeon afk death-knight, at the end of the dungeon after i carry his *** the entire dungeon he decides to need on https://www.wowhead.com/wotlk/item=2...lm-of-the-bold , wins it and insta-leaves.
And i'm horde.
After logging in on alliance char and cursing on him for a while he says 'ok i'll send it to you'. And i'm like... how the fck you're gonna send it to me when my tank warr is horde?!
And of course i'm not dealing with ninja report again because i didnt make screenshot at the beginning and certain brain-farted gm will come again asking for screenshot from 30min ago at the start of the dungeon and whatever...

So! Why dont you allow mailing of items between chars from different factions who participated in a RDF and "by some strange and bizarre mistake" happened to have the wrong item in their bag, so that slightly *****ic part with the screenshot is skipped, apart from all the ninja-reporting itself?

THANK YOU

People would just end up exploiting it. Say I want to sell some items on the horde AH, because the prices on alliance are extremely low, I would then just join the an RDF of another account, leave and then just send all the **** I want sold.