A P7S file is an e-mail message that includes a digital signature. This means that it can be used to send encrypted emails, which can be opened and therefore only viewed by the recipient in question.

P7S files work like this: checks that the email is the correct which is received by the recipient, and prevent the mail from being changed by someone else on the way.

But how to open P7S files on Windows, Mac and Linux? Let’s try to find out together which programs you can use.

How to open a P7S file on Windows, Mac and Linux?

Most e-mail applications can support digital signatures of P7S files. This means that if you use mail clients like Microsoft Outlook and Apple Mail, you should have no problem opening P7S files on Windows, Mac and Linux.

However, what can you do if an e-mail program does not support digital signatures, and does not know how to manage them? In this case you will need to download the P7S file as an attachment to the message (.p7s), and open it using specific clients. This is a method that works for one simple reason: the aforementioned software supports the PKCS (Public Key Cryptography Standard) cryptographic format. But what are these programs that allow you to do this?

How to open a P7S file on Windows?

On the Windows platform you have several options to open your P7S file as an attachment. But it is first of all the case to remind you that you can easily open it with Microsoft Outlook: an e-mail client that supports PKCS and allows you to read digitally signed e-mails without downloading anything else. If you do not use this client, you can still open P7S files as an attachment, using other software.

For example, PostBox is a great alternative client that gives you this opportunity: and it is also very nice and clean from an interface point of view. Alternatively, know that you can open P7S attachments using Mozilla Thunderbird: even in this case it is an alternative and very fast client.

How to open a P7S file on Mac?

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Even on Mac, the systems you can use to open a P7S file are almost identical to Windows platforms. This means that you can use both PostBox and Mozilla Thunderbird: both clients, in fact, are compatible as they also have a version for MacOS. Obviously on Mac you will not be able to use Microsoft Outlook, but it is a false problem: the native client of the Bitten Apple (Apple Mail) is perfectly able to read e-mail messages containing digital signatures.

How to open a P7S file on Linux?

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On Linux you have very few options at your disposal. Obviously you can not use either Microsoft Outlook or Apple Mail. Furthermore, there is no version of PostBox compatible with this open source operating system.

On the other hand, you will have no problem using Mozilla Thunderbird to open a P7S file with digital signature: we can assure you that it will be enough for you to not regret any of the options that we have illustrated in the previous paragraphs. Mozilla Thunderbird, in fact, is one of the fastest and easiest mail clients ever.