I am not sure, Game says you need to have a subscription and expac. If it won't allow you to use mailbox or AH I am pretty sure you will not be able to trade.
per the link above:
You do not have access to the following while on the Starter Edition:
Expansion content (quests, zones, etc).
Characters above level 20.
Pet Battles.
Other chat channels and whispers to non-friends.
All guild-related functions.
Value added services (character transfers, faction changes, etc).
Party formation.
Disabling experience gains.
Trade, mail, or the Auction House.
This post was edited by jshill103 on May 6 2015 01:53pm