.P7M File Extension
There is only one filetype that uses .P7M file extension and it is P7M Email Message.
P7M Email Message
| File category: | Miscellaneous Files |
|---|---|
| Developer: | RSA Data Security |
| Open with: | Microsoft Outlook (+4 more) |
| Platforms: | Windows, macOS, Linux, iOS, Android, iPadOS |
A P7M file is an S/MIME (Secure/Multipurpose Internet Mail Extensions) encrypted or digitally signed email message. When you encounter a P7M file, it typically means you've received a secure email that has been either encrypted for privacy or digitally signed to verify the sender's identity.
These files most commonly appear in web-based email clients when they attempt to display an S/MIME encrypted message but lack the proper capabilities to decode it. Instead of showing the actual message content, these email programs display an empty message with a P7M file attachment (usually named smime.p7m).
The P7M extension indicates a PKCS #7 MIME message. PKCS #7 (Public-Key Cryptography Standards #7) is a standard that defines the format for cryptographically protected messages, while MIME refers to the internet standard for supporting attachments in email.
S/MIME was first introduced in 1995 as a method to add security features to standard MIME messages. The P7M format evolved from this standard as part of the cryptographic message syntax developments in the late 1990s.
How P7M Files Are Used
P7M files serve several important purposes in secure communications:
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Email encryption: Organizations use P7M files to protect sensitive information like financial data, medical records, or confidential business communications when sent via email.
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Digital signatures: P7M files can contain digital signatures that verify the sender's identity and ensure the message hasn't been altered in transit.
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Regulatory compliance: Many industries with strict privacy regulations (healthcare, finance, legal) use S/MIME encryption to meet compliance requirements for secure communication.
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Authentication: The format helps verify that an email genuinely came from the claimed sender.
To use S/MIME encryption and create or receive P7M files properly, users need to install an S/MIME certificate and link it with their email client, such as Microsoft Outlook or Apple Mail.
How to Open .P7M as P7M Email Message
To open a P7M file, you need appropriate software and potentially the correct cryptographic keys:
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Email clients with S/MIME support: Microsoft Outlook, Apple Mail, and Thunderbird (with add-ons) can open P7M files if properly configured with the necessary certificates.
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Specialized viewers: Cryptigo p7mViewer (for Windows) is specifically designed to open and view P7M files.
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Key requirements:
- For signed-only P7M files: You can often open these without special keys
- For encrypted P7M files: You need the appropriate private key that matches the certificate used for encryption
How to Convert an P7M File
P7M files can be converted to standard email formats or other document types once they've been decrypted:
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To standard email formats: Once a P7M file is opened with the proper S/MIME-capable email client, you can save the contents as a regular email message (.eml, .msg).
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To document formats: If the P7M file contains document attachments, you can extract and save these in their native formats (PDF, DOCX, etc.) after decryption.
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Conversion tools: Some specialized tools can batch-convert P7M files to other formats, though you'll still need the appropriate cryptographic keys for encrypted content.
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Online converters: While online converters exist, using them for sensitive encrypted files is not recommended as it potentially compromises security.
The most secure approach is to use your properly configured email client with the appropriate S/MIME certificates to open the P7M file, then save the contents in the desired format directly from there.
Applications That Open P7M Files
Windows Apps for P7M Files:
- Microsoft Outlook Free+
- Mozilla Thunderbird Free
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Cryptigo p7mViewer
Free Trial
macOS Apps for P7M Files:
- Microsoft Outlook Free+
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Apple Mail
Included with OS - Mozilla Thunderbird Free
Linux Apps for P7M Files:
- Mozilla Thunderbird Free
iOS Apps for P7M Files:
- Microsoft Outlook Free+
- P7M Viewer Free+
Android Apps for P7M Files:
- Microsoft Outlook Free+
- Mozilla Thunderbird Free
iPadOS Apps for P7M Files:
- P7M Viewer Free+