Sending message with digital signature


i have just bought digi certificate and imported into macOS MAIL. However, when sending test message to other my email address with Em Client 8.2, message it self is readable (body of the email), but there is annoying attachment smime.p7s

Does it mean that Em Client 8.2 can not handle emails with digital signature sent from Mail app (macOS)?

or smime.p7s file in the attachment will be shown all the time?

Or did i send the test message incorrectly? Could you please confirm the behaviour?

Thank you very much

Kind Regards,

The SMIME.p7s file format is the “digital signature” that is sent alongside a digitally signed email. So that is normal to see that .p7s file as well with the email message & should be showing there.

eM Client support documentation on “Email Encryption and Digital Signature”.

To send an encrypted email to someone, you need their public key (so for the address you are sending to) as well as your own private key (so for the address you are sending from).

Then, before you send the message, click the encryption icon.

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Well, to me its still very strange.

Here is a little example:

1/ sending email from macOS Mail client - from gmail address (apples thick client). i have ticked inside the message, that email will be digitally signed - as there is icon reference for it.

  • i have sent this email in fact to two email addresses (filled in the “To:” field) blahblah@gmail.c*m +
    2/ then i have checked results:
  • in via web interface from web browser, its appearing as standard email message. No signs that it contains digital signature whatsoever
  • in via web interface, there is attachment “smime.p7s”
    3/ i have also double checked the result for blahblah@gmail.c*m also in apples Mail thick client and there is no attachment and icon or what so ever that email was signed.


  • Why some email servers have it with attachment “smime.p7s”
  • Why others dont (e.g. google.c*m)
  • Why in email (thick) clients e.g… “Em Client” or “Mail” (apple) there is no sign that email message was electronically signed with eSignature (certificate).

Thank you

There is. Sent or received messages that are signed will have this in the message preview:

Well, i dont see in Em Client (8.2 in default) what you see.

I have sent eSigned email from gmail (Apples Mail client) to hotmail (which i read via Em Client). When i open the received email from Em Client i dont see and sign that email has been digitally signed

Maybe it isn’t signed.

How does it appear in other applications?

Yesterday i have sent it to a friend and he informed me that at first it appeared that the signature is not valid or considered as untrustworthy. However after a moment he informed me that the status has changed to valid and trustworthy itself… (he did nothing, just displayed detail information. No manual setup to trust it).

Please PM me, and provide me email , i would like to test it. For me this behaviour is quite strange because its official certificate that i have paid for 1 year subscription fee (PostSignum Qualified CA 4)

If the recipient doesn’t have your public key, it will indicate there may be an issue as there is no way to verify the message has not been tampered with. Once the key is imported, and if the message has not been tampered with, it will show as signed.

Well, its odd, if i understood you correctly, then my eSignature will never be presented as valid or trustworthy unless i distribute my public key upfront to the receiver?

c’mon i thought that this process that you have just explained is only description for “encrypted” messages but not for eSignature

That is why by default your public key is sent with the message that is signed. Unless you changed the setting, it should be included.

Or you can upload your key to a public key server, and hope that the recipient can find it there.

How else do you expect a signature to be verified if the recipient doesn’t have the key?

Ok, then why its not working by default if my public key is sent with the message that is signed

Please send me a test message, and sign it. My address is

It looks OK to me.

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