Instead of storing messages, a simple field you can edit (up to, say, 5000 words) added to your characters info page would be nice. This would allow you to keep personal notes on all kinds of things, including message drafts. Afaik that would be easier to code as no storage of recipient is needed, only a text field that saves entered data, doesn't get wiped, can be edited and only accessed by the character.
I would be happy with that.
