How to mail a letter to an inmate at California Men's Colony

To write to someone held at California Men's Colony, address your envelope to the inmate's full committed name and CDCR number, California Men's Colony, P.O. Box 8101, San Luis Obispo, CA 93409-8101. California Men's Colony is a state prison in San Luis Obispo, California, operated by the California Department of Corrections and Rehabilitation.

Inmate mail — California Men's Colony

[Inmate's full committed name]  [CDCR number]
California Men's Colony
P.O. Box 8101
San Luis Obispo, CA  93409-8101

Put the inmate's full committed name and CDCR number on the first line, and mail to the institution's inmate-mail address here — not its street address. Mail without a usable name and CDCR number is returned.

Verified August 2026cdcr.ca.gov cdcr.ca.gov

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California Men's ColonyP.O. Box 8101San Luis Obispo, CA 93409-8101

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Key facts

Send mail to California Men's Colony, P.O. Box 8101, San Luis Obispo, CA 93409-8101 — the institution's inmate-mail address, not its street address.
California Men's Colony is located at Colony Drive, San Luis Obispo, CA, but inmate mail must go to the mailing address above — a letter sent to the street address can be returned.
California delivers inmate mail to each prison directly — but to the institution’s inmate-mail P.O. box, not its street address. Address it to the person’s full committed name, CDCR number, and housing/bed.
Several CDCR prisons use a different P.O. box for each housing facility (yard). Confirm the person’s current housing and use the matching box, or the letter is delayed.
Include your full name and return address. Mail without the correct CDCR number, or without a return address, can be rejected or returned.
Incoming personal mail is opened and inspected for contraband before it is delivered. Keep to plain letter-size paper; send copies of anything you are not willing to lose.
People are transferred between prisons without notice — check CDCR’s inmate locator for the current institution and housing before you mail anything.
PostPal prints and mails your letter for you the next business day for $5 — with your return address printed so the inmate can write back, and no printer, envelope, or stamp needed.

How to send your letter

1
Confirm the person is still at California Men's Colony
Inmates are transferred between facilities without notice. Confirm they are still at California Men's Colony — and double-check the CDCR number — before you mail anything, using the California Department of Corrections and Rehabilitation (CDCR)'s official inmate locator.
2
Address it exactly
First line: the inmate's full committed name and CDCR number. Then California Men's Colony, P.O. Box 8101, San Luis Obispo, CA 93409-8101. Add your full return address.
3
Keep the contents allowed
Plain letter-size paper is safest. Do not enclose cash, stamps, gift cards, or any object other than paper — prohibited items get the whole letter rejected. Check the mail rules above before adding photos.
4
Send it without a printer
Write or upload your letter to PostPal with this address prefilled, and we print, envelope, and mail it via USPS the next business day for $5 — your return address printed so they can reply.

Common questions

How do I address a letter to an inmate at California Men's Colony?

Put the inmate's full committed name and CDCR number on the first line, then California Men's Colony, P.O. Box 8101, San Luis Obispo, CA 93409-8101. Include your full first and last name and return address on the envelope.

Is mail to California Men's Colony opened, read, or scanned?

Expect it to be. Incoming personal mail is opened and inspected for contraband and can be read under the California Department of Corrections and Rehabilitation (CDCR)'s rules.

What can I send to California Men's Colony — photos, cards, or books?

Standard photo prints are generally allowed, usually limited in number and no larger than 8" x 10". No polaroids, and nothing nude, sexually explicit, or gang-related. Books, magazines, and newspapers must come directly from an approved publisher or vendor — they cannot be sent as personal mail.

What can't I mail to California Men's Colony?

Do not send: Cash, checks, money orders, or postage stamps; Any item other than paper (no polaroids, laminated cards, or enclosures); Nude, sexually explicit, or gang-related photos or content; Stickers, glitter, glue, tape, perfume, lipstick, or crayon/marker; Paper treated with any substance, or anything with drug residue. Prohibited items get the letter rejected or destroyed.

What if the person has been transferred or released?

The letter will not reliably reach them or come back to you. Confirm they are still at California Men's Colony before mailing, since the California Department of Corrections and Rehabilitation (CDCR) moves people without notice.

Can the inmate write back to me?

Yes, if you include a complete return address. Inmates can send outgoing mail, though they may need to cover their own postage. PostPal prints your return address for you.

Sources

Addresses verified August 2026 against official sources. Always confirm on the official site before time-sensitive filings.

See the full California inmate mail rules — what you can and can’t send, photos & more →