You can write to Bro Khalfani directly: please only handwritten letters on white paper (lined paper)*! IDOC has ridiculous rules for writing its inmates, and a challenge is being run against these authoritarian rules.):

Bro. Khalfani Malik Khaldun,
Leonard McQuay #874304
Wabash Valley C.F.
P.O. Box 1111,
Carlisle, IN 47838

According to IDOCWatch, a ruling on Sept. 24th 2018 makes it possible to send greeting cards and articles in to prisoners again, for the duration of the ACLU litigation against this repressive mail policy:

“Judge William T. Lawrence of the United States District Court for the Southern District of Indiana has ordered that the IDOC’s policy cannot be enforced for the duration of the litigation. The argument came from Mr. Ken Falk of the ACLU who claimed the policy violated inmates First Amendment Rights and served no “legitimate penological function” that could not be achieved with less burdensome means.

The injunction which will take effect 30 days following the September 24th ruling will allow outside supporters to send greeting cards, articles, and other similarly banned materials while the suit is still in the courts.” (IDOCWatch)