My ex continued to send me messages for about 9 months after I left her, and as I got some distance and learned about the disorder all of the messages became transparent and ridiculous, and most importantly, had no impact on me except curiosity and amusement.
If you look at it from the perspective of a borderline trying to retain an attachment, because attachments are absolutely everything to borderlines, it can desensitize you to the emails and actually become amusing. And you can even make it a game, since god knows we could use a little fun after all we've been through.
"Found old emails. Made me smile. Hope you are well."
Translation: "I have emotions I can't soothe right now, so I used old emails and idealizing you made me feel better, and 'hope you are well' is pure bait to see if you may be of use to me again."
Pretty funny when you think about it... .