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How to send a letter to an inmate at Boulder County Jail

To write to someone held at Boulder County Jail, address the envelope to the inmate's full name and inmate ID number, c/o Boulder County Jail, 3200 Airport Road, Boulder, CO 80301. Boulder County Jail is the jail for Boulder County, Colorado, run by the Boulder County Sheriff's Office. Mail is opened and inspected — include your full return address, and double-check the person is still in custody, since people are released or moved from a county jail quickly.

Inmate mail — Boulder County Jail

[Inmate's full name]  [inmate ID number]
c/o Boulder County Jail
3200 Airport Road
Boulder, CO  80301

Put the inmate's full name and inmate ID number on the first line, and your full return address in the corner — mail without either is usually rejected.

Verified August 2026bouldercounty.gov

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Your name
Your return address

c/o Boulder County Jail3200 Airport RoadBoulder, CO 80301

Your letter, printed and mailed for you.

Key facts

  • Send mail to c/o Boulder County Jail, 3200 Airport Road, Boulder, CO 80301 — the jail's own mailroom.
  • Write the inmate's full name and inmate ID number on the envelope, plus your full return address, or the letter is returned.
  • All incoming mail is opened and inspected for contraband before it reaches the inmate.
  • Do not enclose cash, checks, gift cards, or anything other than paper — prohibited items get the whole letter rejected.
  • Inmates may receive letters in sealed envelopes; all incoming mail is read.
  • Blue or black ink; no drawings, glitter, or confetti.
  • No return envelopes, nude or explicit photos, or hardcover books.
  • County jails move fast — people are released, bailed out, or transferred within days. Confirm the person is still in custody before mailing anything time-sensitive.
  • PostPal prints and mails your letter for you the next business day for $5 — with your return address printed so they can write back, and no printer, envelope, or stamp needed.

How to send your letter

  1. 1

    Confirm the person is still at the jail

    County-jail populations turn over quickly. Check the Boulder County Sheriff's Office's online inmate roster to confirm they're still at Boulder County Jail — and get their inmate ID number — before you mail anything.

  2. 2

    Address it correctly

    First line: the inmate's full name and inmate ID number. Then c/o Boulder County Jail, 3200 Airport Road, Boulder, CO 80301. Add your full return address in the top-left corner.

  3. 3

    Keep the contents allowed

    A plain letter on white paper is always safest. Inmates may receive letters in sealed envelopes; all incoming mail is read. No cash, gift cards, or any object other than paper.

  4. 4

    Send it without a printer

    Write or upload your letter in 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 Boulder County Jail?

Put the inmate's full name and inmate ID number on the first line, then c/o Boulder County Jail, 3200 Airport Road, Boulder, CO 80301. Include your full return address in the top-left corner of the envelope.

Is mail to Boulder County Jail opened or read?

Yes. All incoming mail is opened and inspected for contraband before delivery, and non-legal mail can be read.

What if they've been released or moved?

It happens fast at a county jail — people bond out or transfer within days, and the letter won't be forwarded. Check the Boulder County Sheriff's Office's inmate roster to confirm they're still at Boulder County Jail before you send.

What can I send to Boulder County Jail?

Inmates may receive letters in sealed envelopes; all incoming mail is read. Blue or black ink; no drawings, glitter, or confetti. No return envelopes, nude or explicit photos, or hardcover books. When in doubt, a plain letter on white paper is always accepted.

Can the inmate write back to me?

Yes, if you include a complete return address. PostPal prints your return address on the letter for you.

Sources

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

See the full US county & city jails rules — what you can and can’t send, photos & more →

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