The envelopes are posted among the letters - this is not a thorough list but on quick review I noted envelopes were sent to Tracy on:
Oct 21, 24, and 30,
Nov. 4, 14 and 20,
Dec. 02 and 29* of 2008;
Jan. 05* and 30,
Feb. 12 and 25 of 2009.
*looks like two envelopes went out on these days.
pdf. 121 (pg. 13705-6)
letter dated 10/27/08 "Thanks for doing something with Casey Anthony's notes, I certainly can't keep them in my cell with me since she is so high profile."
pdf. 62 (pg. 13656)
letter dated 2/23/09 "Dear Tracy, I have to get rid of these notes from Casey so she doesn't get in trouble too. Do you think one day they'll be worth anything? Maybe a spot on the Today Show or Oprah if anything comes of it, who knows, I am her only friend here but that might be like betrayal and I don't want that!..."
pdf. 98-101 (pg. 13682-85)
letter dated 4/3/09 "Dear Tracy, First, I want to begin by apologizing for hurting your feelings and making you angry with my stupid words in my journal. I would never intentially hurt you, I am so sorry and feel horrible for making you upset. You mean the world to me and I cherish our friendship as I do a sisterhood. The only reason Casey confides in me as much as she does is because she has no one to talk to and for some reason she feels comfortable opening up to me, I'm honestly not sure why that is. This may be my only way out of prison sooner than my expected term.* ... I did think that they might hold some value in the future but that's as far as I thought."
*BBM
Also see pages 13714, 13761, 13611 among others.
Not posted here is the reference to the letter that Robyn writes about how she was betrayed by someone which is why she ended up in prison. In that letter, she prides herself for not being the person who did the betraying. Go figure!