To send a letter to an inmate, address the envelope to the person’s full legal name and inmate ID number at the facility’s official mailing address, write on plain white paper in blue or black ink, enclose nothing but the letter itself, and put your full return address in the upper left corner. Every U.S. correctional facility accepts physical mail, but each sets its own rules on top of the system-wide ones, and getting a small detail wrong is enough to have the letter returned or confiscated.
Find the Facility and the Inmate ID Number
Before writing anything, confirm where the person is currently held and get their identification number. That number goes on every piece of mail and is the single most important detail for delivery. Without it, staff in a facility housing thousands of people have no reliable way to match your letter to the right person, particularly when names are common.
For federal custody, the Bureau of Prisons runs an online inmate locator that searches by name or BOP register number and returns the facility name and location. It covers anyone incarcerated in a federal facility from 1982 to the present.1Federal Bureau of Prisons. Inmate Locator For state prisons, the state Department of Corrections website has a similar lookup. County jails are usually searchable through the local sheriff’s office. Each system assigns its own ID format: the BOP register number looks like 12345-678, while states use DOC numbers, booking numbers, or SID numbers. Write down the full legal name and the ID number before you start.
Inmates transfer between facilities without much notice. If a letter comes back to you, check the locator again before resending rather than assuming the old address still works.
How to Address the Envelope
Federal and most state facilities use the same basic format:
- Line 1: Inmate’s full legal name and identification number
- Line 2: Name of the correctional facility, plus housing unit if you know it
- Line 3: Facility street address or PO Box
- Line 4: City, state, and ZIP code
Your return address goes in the upper left corner with your full name and complete mailing address. Federal regulations require a return address on all inmate correspondence, and most states do too.2eCFR. 28 CFR Part 540 Subpart B – Correspondence A missing or incomplete return address can get the letter rejected outright. Use the facility’s official mailing address exactly as it appears on the corrections department website; some facilities route all mail through a central processing address rather than the physical prison.
Paper, Ink, and Envelope
Most facilities restrict you to plain white paper written in blue or black ink. Colored paper, construction paper, and lined notebook paper with spiral-edge fragments are commonly rejected. Many facilities also require plain white envelopes in standard sizes (a No. 10 business envelope or smaller) and reject padded, oversized, or colored envelopes.
Crayons, markers, gel pens, and anything that leaves a heavy or glossy residue are typically prohibited. These material rules exist because substances can be dissolved into dyes, inks, and coatings and absorbed into the paper itself; the BOP’s own policy changes have specifically referenced synthetic drug smuggling as the reason for tightening them.3DC Corrections Information Council. Federal Bureau of Prisons Mail Policy Changes as of November 13, 2017 A standard ballpoint pen on regular copy paper is safe almost everywhere. Check the specific facility’s mail page before sending, because individual institutions sometimes add restrictions beyond the system-wide rules.
What You Cannot Enclose
The list of prohibited enclosures is long, and it catches most first-time senders on small things they wouldn’t think twice about. Items commonly rejected across federal and state facilities include:
- Adhesives of any kind: stickers, tape, return address labels, sticky notes, glued decorations
- Loose materials: glitter, confetti, sand, dried flowers, or anything that falls out of the envelope
- Metal or hard objects: staples, paper clips, brads, coins
- Stamps and stamped items: envelopes with postage already affixed or unused stamps enclosed
- Scented materials: perfume, cologne, scented paper or stickers
- Food or liquids: gum, candy, lipstick or chapstick marks on the paper
Federal facilities specifically prohibit sending stamps or stamped items to inmates. Anything received that way is returned at government expense with a notice explaining the restriction.4Federal Bureau of Prisons. Mail Management Manual Cash, credit cards, and phone cards are also prohibited. Under federal law, currency itself is classified as a prohibited object inside a prison, and providing it to an inmate carries criminal penalties.5Office of the Law Revision Counsel. 18 US Code 1791 – Providing or Possessing Contraband in Prison
What You Cannot Write
Content is inspected too. Facilities can reject correspondence that contains threats, information about escape plans or criminal activity, coded language, or sexually explicit material.6Federal Bureau of Prisons. Correspondence The warden has broad discretion to reject anything deemed detrimental to institutional security or good order. Assume anything you write in a general letter could be read by someone other than the inmate.
Photographs, Books, and Money
Photos are one of the most valued items inmates receive, but they have their own rules. Most facilities accept standard printed photos (typically 4×6 inches) and prohibit Polaroid-style instant photos, because the layered construction and chemical coating can conceal contraband that a standard print cannot. Federal policy specifically bars personal photographs showing nudity, exposed genitalia, exposed female breasts, or sexually suggestive acts. The standard is whether the photo would be detrimental to safety, security, or institutional order if the inmate had it.6Federal Bureau of Prisons. Correspondence Family photos, kids, pets, holidays, and everyday life are exactly what facilities expect and allow. Many facilities cap the number of photos per envelope, commonly between five and ten, and some accept only commercially printed photos rather than home-printer output.
Books are handled separately from letters. You generally cannot drop a book into a package and mail it. Most correctional systems require books, magazines, and newspapers to come new and directly from a publisher or an approved retailer, shipped straight to the facility. Used books, hardcover books in some facilities, and books with spiral binding are frequently rejected.
Money cannot go inside a letter. Commissary deposits are handled through a completely separate process. For federal inmates, the BOP accepts money orders, cashier’s checks, certified checks, and U.S. government checks mailed to a centralized lockbox; personal checks and cash are not accepted.7Federal Bureau of Prisons. Sending Funds Using the United States Postal Service Most state systems use electronic deposit platforms or retail options like MoneyGram. Never tuck cash or a money order inside a regular letter. At best it comes back; at worst the letter is confiscated.
What Happens After It Arrives
Correctional staff open and inspect incoming mail before the inmate sees it. Federal regulations give institutions the authority to open all general correspondence addressed to inmates and to read it “as frequently as deemed necessary to maintain security or monitor a particular problem confronting an inmate.”2eCFR. 28 CFR Part 540 Subpart B – Correspondence
Delivery timelines vary. Some facilities pass mail along within a day or two of arrival at the mailroom; others take a week or more, especially during lockdowns, high-volume periods, or facility-wide inspections.
A change worth knowing about: a large and growing number of correctional systems no longer hand inmates the physical letter you sent. Incoming mail is scanned or photocopied, and the inmate receives a digital image on a tablet or a black-and-white paper copy. As of early 2026, a substantial majority of state prison systems use some form of mail scanning or photocopying rather than delivering the original. What happens to the original depends on the system: some hold it for the inmate to collect on release, many destroy it after scanning, and a handful still deliver mail as received. Cut-off margins, missed backsides of double-sided pages, and blurry images have been common complaints. If the facility scans mail, keep the layout simple and write only on one side of each page.
Legal Mail Is Different
If you’re writing as an attorney, or on behalf of a court, member of Congress, the U.S. Department of Justice, a governor, or certain other government officials, the general-mail rules above do not apply the same way. Under federal regulations, this “special mail” must be opened only in the inmate’s presence and may be inspected for physical contraband only. Staff cannot read or copy it.8eCFR. 28 CFR 540.18 – Special Mail
To trigger the protection, the sender must be clearly identified on the envelope, and the front must be marked “Special Mail — Open only in the presence of the inmate.” Variations like “Attorney-Client — Open only in the presence of the inmate” or “Legal Mail — Open only in the presence of the inmate” are also accepted.6Federal Bureau of Prisons. Correspondence Without both the identification and the marking, staff can treat the letter as general mail and read it normally.
If Your Letter Is Rejected
If a letter violates a facility’s mail rules, it gets rejected. Under federal regulations, the warden must notify both the sender and the inmate in writing, explaining the reason and informing both parties of their right to appeal. Rejected mail is generally returned to the sender. The exceptions: a letter containing evidence of criminal activity or plans to commit a crime can be forwarded to law enforcement without notice, and physical contraband found in mail is confiscated and not returned.9eCFR. 28 CFR 540.13 – Notification of Rejections Common reasons for rejection include stains or discoloration on the paper, adhesive materials, incorrect addressing, prohibited enclosures, or content that violates institutional rules.
Criminal Penalties for Contraband
Including prohibited items in mail to an inmate is not just a policy problem that gets your letter returned. Under federal law, providing contraband to a prison inmate is a crime. Penalties scale with the severity of the object:5Office of the Law Revision Counsel. 18 US Code 1791 – Providing or Possessing Contraband in Prison
- Up to 20 years for narcotics, methamphetamine, LSD, or PCP
- Up to 10 years for firearms or destructive devices, or Schedule I or II controlled substances other than the drugs listed above
- Up to 5 years for marijuana, Schedule III substances, ammunition, or weapons other than firearms
- Up to 1 year for other controlled substances, alcohol, currency, or cell phones
- Up to 6 months for any other object that threatens institutional order, discipline, or safety
Any sentence for a contraband violation involving controlled substances runs consecutively to any other drug-related sentence, not concurrently.5Office of the Law Revision Counsel. 18 US Code 1791 – Providing or Possessing Contraband in Prison Most people whose letters are rejected are not facing criminal prosecution for an accidental sticker or paper clip. But the last category is broad, and state facilities also impose administrative consequences, including permanent bans from the approved correspondence and visitor lists. Follow the mail rules exactly, and when in doubt, leave it out.