I may have suggested something similar before, or someone has already suggested it...(I've did a quick search on the forums and couldn't find anything).
What about the idea of mail boxes? Players are able to send letters and items to each other within game.
Any players can access their mail from any mail box. (For example, accessing these forums from any computer with an internet access.)
The letter boxes can be placed outside inns in cities/towns/villages.
Players will have to pay x amount to send mail or a parcel, and you could have a time limit to send...for example 30 minutes for a parcel to arrive to the mail box. Whilst letters can have like a 10 minute delivery.
If it's trading, you could do a "Cash on Delivery" service, I.E I send to another player two platinum ores each costing 1,000 coins each, and the recieveing player can only open the mail if they pay the fee first, and the fee of 2,000 coins is sent back to the original player.
Or instead of mail boxes, you could have a post office instead -- But were they around in the times were RPing with now?
Problem with this is that same-players can easily maul items to other characters probably without being traced. Also I have a slight feeling it may abolish the whole LORE-message-in-game idea.
Comments?