WotLK Sending heirlooms cross faction

[EtoZheDante]

Can i mail in-game heirlooms from horde to alliance if they are on the same realm and same account?

[skullatbash]

yes.
"Bind to account" = you can send it even if it is opposite faction ( need to be same account and same realm)

Be sure to not enchant that heirloom, otherwise the item becomes "soulbound"

[EtoZheDante]

Thank you!

[OhieMitzen]

yes.

Be sure to not enchant that heirloom, otherwise the item becomes "soulbound"

Yes and no. Basic enchants that are done by enchanter won't make the heirlooms soulbound. Such as weapon, chest enchants.

In WotLK enchants that makes the items soulbound: LW's wrist enchants, scribe's shoulder enchant (and Sons of Hodir rep enchants), enchanter's ring enchant. <- They all specifically state that "doing this will make the item soulbound", meaning it's better not to use these on heirlooms.
Further expansions provides more heirloom backs, heads and legs. These too can become soulbound if enchanted by profession's own enchants:
Back - Tailoring
Legs - Tailoring (any of them, spellthreads or embroiderys)
Head - Reputation head enchants from WotLK (don't recall there being profession enchants to head slots)

What can I enchant the items with? From an enchanter any enchant with no level requirement mentioned.