P7S File Extension

What is P7S file?

P7S file is a email message secured with digital signature. Digital signature guarantees that the file was not modified in transit and both sender and recipient are who they claim to be. Digital signature thus precludes possibility of the message being tampered with by a third-party if captured.

Digital signature support

Email messages in P7S files are digitally signed using PKCS #7 (Public-Key Cryptography Standard) technology, and to open such message user needs to use email client that supports this standard. Most email applications recognize digital signatures, but some don’t. In the latter case P7S file will be listed as attachment with smime.P7S filename.

Programs which support P7S file extension

Below you will find an index of software programs that can be used to open P7S files divided into 3 categories according to system platform supported. Files with P7S suffix can be copied to any mobile device or system platform, but it may not be possible to open them properly on target system.

Updated: 01/05/2020

How to open file with P7S extension?

Being unable to open files with P7S extension can be have various origins. On the bright side, the most encountered issues pertaining to Digitally Signed Email Message files aren’t complex. In most cases they can be addressed swiftly and effectively without assistance from a specialist. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Get the Mozilla Thunderbird

The main and most frequent cause precluding users form opening P7S files is that no program that can handle P7S files is installed on user’s system. This issue can be addressed by downloading and installing Mozilla Thunderbird or different compatible program, such as Apple Mail, PostBox, Microsoft Outlook. The full list of programs grouped by operating systems can be found above. One of the most risk-free method of downloading software is using links provided by official distributors. Visit Mozilla Thunderbird website and download the installer.

Step 2. Update Mozilla Thunderbird to the latest version

If the problems with opening P7S files still occur even after installing Mozilla Thunderbird, it is possible that you have an outdated version of the software. Check the developer’s website whether a newer version of Mozilla Thunderbird is available. It may also happen that software creators by updating their applications add compatibility with other, newer file formats. The reason that Mozilla Thunderbird cannot handle files with P7S may be that the software is outdated. All of the file formats that were handled just fine by the previous versions of given program should be also possible to open using Mozilla Thunderbird.

Step 3. Associate Digitally Signed Email Message files with Mozilla Thunderbird

If you have the latest version of Mozilla Thunderbird installed and the problem persists, select it as the default program to be used to manage P7S on your device. The process of associating file formats with default application may differ in details depending on platform, but the basic procedure is very similar.

The procedure to change the default program in Windows

• Choose the Open with entry from the file menu accessed by right-mouse clicking on the P7S file
• Click Choose another app and then select More apps option
• Finally select Look for another app on this PC, point to the folder where Mozilla Thunderbird is installed, check the Always use this app to open P7S files box and conform your selection by clicking OK button

The procedure to change the default program in Mac OS

• From the drop-down menu, accessed by clicking the file with P7S extension, select Information
• Proceed to the Open with section. If its closed, click the title to access available options
• Select the appropriate software and save your settings by clicking Change all
• Finally, a This change will be applied to all files with P7S extension message should pop-up. Click Continue button in order to confirm your choice.

Step 4. Verify that the P7S is not faulty

Should the problem still occur after following steps 1-3, check if the P7S file is valid. Problems with opening the file may arise due to various reasons.

1. The P7S may be infected with malware – make sure to scan it with an antivirus tool.

Should it happed that the P7S is infected with a virus, this may be that cause that prevents you from accessing it. Scan the P7S file as well as your computer for malware or viruses. If the scanner detected that the P7S file is unsafe, proceed as instructed by the antivirus program to neutralize the threat.

2. Check whether the file is corrupted or damaged

If you obtained the problematic P7S file from a third party, ask them to supply you with another copy. The file might have been copied erroneously and the data lost integrity, which precludes from accessing the file. When downloading the file with P7S extension from the internet an error may occurred resulting in incomplete file. Try downloading the file again.

3. Ensure that you have appropriate access rights

There is a possibility that the file in question can only be accessed by users with sufficient system privileges. Log in using an administrative account and see If this solves the problem.

4. Check whether your system can handle Mozilla Thunderbird

The operating systems may note enough free resources to run the application that support P7S files. Close all running programs and try opening the P7S file.

5. Check if you have the latest updates to the operating system and drivers

Up-to-date system and drivers not only makes your computer more secure, but also may solve problems with Digitally Signed Email Message file. It is possible that one of the available system or driver updates may solve the problems with P7S files affecting older versions of given software.

Do you want to help?

If you have additional information about the P7S file, we will be grateful if you share it with our users. To do this, use the form here and send us your information on P7S file.