If she can't trust Lucia with a messenger, she can't trust her in general, but still, no need to get sloppy.  Just because Asmodeus's hold over the land is broken his treachery lives on. Thea reads the letter over once normally, then again normally.

"Everything seems to be in order.  Excellent.  It will be Ilda bearing the letter... I can give her my older improvised divine focus with Irori's holy symbol that I used before my current divine focus.  She'll depart tomorrow morning and should be back shortly after the convention's beginning... perhaps a week or two later if she has reason to make full use of the two weeks or runs into delays in her travel."

"Splendid. I look forward to hearing what she thinks!"

And Lucía provides Thea a small purse (with a soft clink of metal), and then stretches out to take a short rest, before heading back to her town-house.