Digital Signatures not received by other email clients

donotgetemail's Avatar


26 Oct, 2017 04:14 PM

I think I'm in love. Airmail is the email client I've always wanted but never knew existed. The main hangup was as I'm demoing it for potential use on staff at our University it lacked S/MIME support. We use digital signatures to verify authenticity of emails. Then I discover the S/MIME plugin. Much to my chagrin it doesn't appear to work correctly.

When I send a message with a digital signature from Airmail, Outlook, or Apple Mail they all show up as signed (verified with blue checkmark) within Airmail, but inside the other clients, the one sent from Airmail shows no digital signature. This has the effect of no one seeing a digital signature when they receive an email from me if they use Apple Mail or Outlook.

I'm using S/MIME Beta 1.0 with Airmail Beta 3.5.3 (459) on macOS 10.13.

It appears that Airmail is not actually attaching the digital signature to the message (via a pkcs7-signature). When I view the raw source of the message I sent from Airmail within Airmail there is a header:

Subject: Test Digital Cert From Airmail
X-Mailer: Airmail Beta (459)
Content-Type: multipart/signed;
boundary="7C8B864C-37A2-41DA-A245-DBA86BBD288F"; protocol="application/pkcs7-signature"; micalg=sha1 MIME-Version: 1.0

That is correct and what you'd expect, but when I view the raw source of the same message from within Apple Mail that section is completely missing. This is a show stopper. Please advise.

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