N.Y. Comp. Codes R. & Regs. tit. 7, § 720.8
(4) An inmate, who has sufficient funds available in his inmate account, may purchase postage by attaching a disbursement form to a letter only in the following circumstances:
(5) An inmate who has lost commissary privileges shall be able to make a monthly “stamp buy” of up to 50 domestic first class stamps for one ounce letters. This special buy shall be offered within 72 hours of the imposition of the penalty and every 30 days thereafter. Inmates who have been admitted to a special housing unit shall be offered a “stamp buy” within 72 hours of admission and every 30 days thereafter.
(b) Free postage.
(3) Inmates may not accumulate, from week to week, credit for unused postage.
(c) Advances for legal postage.
Funds may be advanced to an inmate for the purpose of sending legal mail in accordance with the procedures set forth in Part 721 of this Title.
(d) Advances for personal postage.
Funds may be advanced to an inmate for one domestic first class one ounce letter per month in the following circumstances:
(3) The inmate has lost telephone privileges, has a zero or negative account balance, and has not refused to accept available program assignments.
(e) Inmate organizations.
Inmate organizations must pay the postage costs for all of their outgoing mail.
(a) Purchase/possession of stamps.