How to Send Legal Mail to Prisons in the UK: A Complete Step-by-Step Guide

If you’ve ever needed to send legal documents to someone in prison, you might be wondering: How does it work? Is there a special process? Can I just pop it in the post box like regular mail?

Well, the answer is… not quite.

The UK prison system has strict rules to ensure that legal mail is secure, confidential, and delivered properly. Whether you’re a solicitor, barrister, or simply helping someone access legal help behind bars, it’s crucial to follow the correct procedure. Otherwise, your mail may be delayed—or worse, not delivered at all.

Don’t worry—we’ve broken everything down for you in this simple, step-by-step guide. Let’s get started!

What is Legal Mail?

Legal mail (also called “privileged correspondence”) is any communication between a prisoner and their legal representative. This includes:

• Solicitors and barristers
• Legal advisors and law firms
• Courts and legal bodies

This kind of mail is treated differently from regular mail to protect the prisoner’s right to confidential legal advice. That means it isn’t opened unless prison staff have a reason to check it for security—usually, this is done in the prisoner’s presence.

Now that we know why it matters, let’s look at how to send it properly.

Who Can Send Legal Mail to a Prison?

Good question! Not everyone can send legal mail. To qualify, you must be officially recognised as a legal professional or be sending documents connected to ongoing legal proceedings.

This includes:

• Practising solicitors or legal executives
• Members of the Bar (barristers)
• The courts
• Regulatory and oversight bodies like the Legal Ombudsman
• Tribunals and legal aid authorities

It’s very important not to abuse the legal mail system. Sending unofficial or personal messages disguised as legal correspondence can put the prisoner—or the sender—into hot water.

Things You Need Before Sending Legal Mail

Let’s talk about the essentials. Before you send any legal mail, make sure you have the following:

• The prisoner’s full name and their prison number
• The full address of the prison (double check it’s correct!)
• Your legal firm’s name and address, clearly shown on the envelope
• “Legal mail” written clearly on the front of the envelope

Without all this info, there’s a risk your letter will be treated like standard mail—or worse, sent back to you.

Step-by-Step Guide to Sending Legal Mail to a Prison

Step 1: Write “Private and Confidential” on the Envelope

On the front of the envelope, clearly write:

• “Legal mail”
• “Private and Confidential – Legal Correspondence”

This helps prison staff immediately recognise that this is privileged communication and it needs to be handled differently.

Step 2: Include the Prisoner’s Details

Underneath your legal firm’s address, you must include the prisoner’s full name and prison number. This ensures the letter is directed to the right person.

For example:

John Smith
Prison Number: A1234BC
HMP Example Prison
123 Prison Road
Townville
AB12 3CD

Tip: Not sure of the prisoner’s number or the prison address? You can find it on the official UK government site or by contacting the prison directly.

Step 3: Use a Business Envelope with Your Firm’s Address

The envelope should clearly show your law firm’s name and address. This helps the prison verify that the mail genuinely comes from a legal source.

If your details aren’t visible—or if you use a generic envelope—it may be flagged as suspicious and could be delayed or rejected.

Step 4: Send It via Royal Mail First or Second Class

Yes—it’s that simple. You can simply send the letter via Royal Mail, using either first or second class post.

You do not need to use Recorded Delivery. In fact, most prisons prefer standard post to avoid unnecessary delays.

Step 5: Await Confirmation from the Prisoner (Optional)

Once the prisoner receives your letter, they will usually be able to reply. However, because communication can be slow, don’t panic if you don’t hear back right away.

What if the prisoner says they didn’t receive it? You can follow up with the prison’s legal services department to check on the mail’s status.

What Happens When Legal Mail Arrives at the Prison?

When the mail arrives:

• It goes through a basic security check—without being read or censored
• If necessary, the envelope is opened in front of the prisoner, but the letter remains confidential

The goal is to maintain prison security while protecting the inmate’s right to legal support. It’s a delicate balance—but one that the prison service takes seriously.

Dos and Don’ts of Sending Legal Mail

✅ Do:

• Double-check the prisoner’s details
• Clearly label the envelope as “Legal Mail”
• Include your firm’s address to confirm the sender’s identity
• Stick to only legal-related content

⛔ Don’t:

• Send personal messages disguised as legal letters
• Use nicknames or incomplete prisoner details
• Attempt to hide prohibited items in the envelope

Common Mistakes to Avoid

We all make mistakes, but when it comes to legal mail, a small error can mean a big delay. Here are a few common slip-ups to steer clear of:

• Forgetting to mark the envelope with “Legal Mail”
• Sending paperwork with unclear firm details
• Using incorrect prisoner information—even a small mistake in the number can cause problems
• Including personal or informal content that isn’t tied to legal proceedings

Final Thoughts

Sending legal mail to someone in prison might seem tricky at first—but once you know the steps, it’s actually pretty straightforward. The key is to be clear, professional, and precise in every letter you send.

Think of it like this: would you want important court documents getting lost or delayed? Exactly. That’s why this process matters.

So next time you need to send a letter, just follow these simple steps, double-check your info, and trust the system to handle it securely.

Need More Information?

For full government guidance, visit the official page:
https://www.gov.uk/guidance/send-legal-mail-to-prisons