On the Joanns mailers, I was told by a manager that you not only need to have the coupon scanned to stay on the mailing list - you actually need to have the bar-code by your name scanned. She said if you do that every few months you'll stay on the mailing list, otherwise you're dropped. I've known of several people who just stopped getting their coupon mailers.
And, at least at my Joanns they'll take Michael's coupons.