How should I send confidential and privileged information to a client in prison?

I’m a criminal solicitor. I need to send privileged advice and confidential communications to clients in prison. Should I send these electronically or continue using the rule 39 paper letter?

The Ministry of Justice (MoJ) has developed a Criminal Justice Secure Mail service.

The service enables solicitors to send confidential and privileged information to clients in prison in England and Wales electronically.

It aims to:

  • remove the need for the use of double envelopes and covering letters
  • reduce calls from prisons about the legitimacy of mail received
  • significantly reduce rule 39 confidential mail being opened in error
  • simplify under one scheme how confidential mail is sent to prison

If solicitors have any specific questions about the service, email

For more information on the steps to take before using the service for the first time, see the government’s guide to sending legal mail to prisons.


While every effort has been made to ensure the accuracy of the information in this article, it does not constitute legal advice and cannot be relied upon as such. The Law Society does not accept any responsibility for liabilities arising as a result of reliance upon the information given.

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