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How to Decrypt Outlook Email? Remove S/MIME & OpenPGP Encryption

Mayank | Modified: 14-11-2022 | Forensics | 6 Minutes Reading

Are you looking for a way to decrypt Outlook email? Then, we can help you with an efficient solution for the same. Instantly remove S/MIME & OpenPGP encryption from Outlook email using the trustworthy MailXaminer Email Examiner Software. Analysis of the encrypted emails is commonly faced by forensic investigators during the email investigation of an Outlook email message. With the help of this write-up, you will get detailed knowledge about how to encrypt and decrypt the Outlook emails in an efficient manner.

Decrypt Outlook Email

Why We Need Email Encryption?

Encryption is the most common data security mechanism used to maintain the confidentiality of digital data. The encryption process converts the message or information into a different form, which is only accessed by authorized users. Now, while encrypting the email message from the sender’s side, he/she uses an encryption key which will convert the plain text into ciphertext. If the receiver wants to access the encrypted email message in its original format, then the decryption key is required.

The main aspect behind encryption is that it enables to protect the confidentiality of the digital data while transmitting over the internet. As a result, it helps to protect the data from the intruders. The two main types of encryption used to protect the data are Symmetric-key encryption & Asymmetric key encryption.

  • Symmetric Key Encryption: In symmetric key encryption, same key is being used for encryption and decryption of the data.
  • Asymmetric Key Encryption: It is also known as public-key encryption. In this, for both encryption and decryption processes, different keys are required. The keys are known as the public key and private key.

Before discussing how to decrypt an Outlook email, it is necessary to understand the encryption process of the same. We all know that Microsoft Outlook is one of the most commonly used desktop-based email application. At the same time, Outlook users are pretty much concerned about the security of their data. For that, encryption is the best way to secure all the PST mailbox items. Besides understanding about encryption and decryption of the Outlook email messages. Additionally, we will also shed light on the analysis of emails after removing encryption from an Outlook email message.

Before starting the encryption process, users have to obtain a digital certificate / digital ID and must install it to the Outlook application. There are several Microsoft approved sources available in which COMODO provides S/MIME email certificate and the digital ID which automatically adds the certification.

Digital ID Installation Process

1: Click on the File tab of the Outlook and select Trust Centre from the options

2: Select the Email Security tab from the Trust Centre Settings

3: Under the Encrypted Email section, click on the Settings button and choose New for the security preference

4: Enter the Name for the security settings and select S/MIME for the cryptographic format list

5: Click the Choose button and select the valid certificate for the Digital Signature

6: At last, mark the checkbox corresponding to “Send these certificate with the signed messages”.

After successful installation of the Digital ID, one can easily start with the email encryption process directly.

Now, in the upcoming section, we will describe how to encrypt Outlook emails.

Outlook Email Encryption Process

Encryption of Individual Outlook Emails

1: Navigate to the Options tab from the Outlook application and select Dialog Box Launcher from the More option

2: Now, click the Security Setting button from the Properties window

3: Enable the Encrypt Message Contents and Attachment options from the Security properties

4: After this, you can write and send an email which will be received by the recipient in the encrypted form.

Encryption of All Outlook Emails

With the following steps, one can encrypt all their Outlook emails. Before implementing this procedure, a user must ensure that all their recipients are having the same Digital ID to decrypt the Outlook emails.

1: Click on File tab and go to Trust Centre from Options

2: Select the Email Security tab from the Trust Centre Settings

3: Go to Encrypted Email section and mark the checkbox that corresponds to Encrypt Contents and Attachments for Outgoing Messages option

4: Now, click OK. For changing the Encryption options, click on the Settings button.

With the aforementioned procedure, one can efficiently encrypt Outlook emails. Now, from the below section, we will understand the tactics used to decrypt the Outlook message, which requires the same digital certificate.

Procedure to Decrypt S/MIME/ OpenPGP Encrypted Emails

While performing the forensic analysis of an Outlook email, it is an important factor to decrypt Outlook emails. This is because, most of the time for security reasons, users tend to encrypt confidential email messages. As a result, investigators need to perform the decryption process which requires decryption key. Without the keys, it is not possible to remove encryption from the encrypted Outlook emails.

Following are the steps to remove encryption from the Outlook email using the remarkable computer forensic software.

1: Install and launch the software and click the Add New Evidence option to upload the email data file to the software panel.


2: Then, select the Microsoft Outlook option to add PST file for email decryption. Click Next to configure Encryption Settings to decrypt S/MIME & OpenPGP encryption.


3: Enable Detect Digital Signature and Encryption option and Remove Encryption option from the Encryption Option tab as shown in the image below.

  • Detect Digital Signature and Encryption: This will help to detect the digitally signed and encrypted emails from the mailbox and will be represented with the corresponding tags.
  • Remove Encryption: This option allows to decrypt Outlook email message.


4: Users can add the decryption keys either using the Add Keys option or the Upload CSV option.

add decryption keys

5: Select the Add Keys option and choose the appropriate encryption which corresponds to the file i.e., S/MIME or OpenPGP. After that, provide the Key File and Password of the respective file to remove encryption from Outlook message. Users can also add multiple keys here using the Add Additional Keys option.


6: In order to upload a CSV file to decrypt Outlook email evidence  with multiple keys. You need to choose Upload CSV radio button from the Decryption Settings section and browse the corresponding CSV file.

upload-csv file

Once the process gets complete to decrypt Outlook email message. The decrypted emails can be viewed by switching to the Search screen. After which, the investigation officers can thoroughly examine the decrypted email message.

Final Words

It is quite challenging for forensic investigators to examine encrypted Outlook emails. Hence, there comes a need to decrypt Outlook email. One can seamlessly rely on the steps mentioned in this article to remove encryption from the Outlook message. Moreover, to decrypt SMIME/ OpenPGP encrypted emails, it is a wise option to avail the result-oriented Email Forensics Software.