Bug 469681

Created attachment 158898 [details]
Representative S/MIME encrypted content

SUMMARY
***
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***
Someone sent me (most probably from Apple Mail) 

STEPS TO REPRODUCE
1. Receive an mail, encrypted & signed with S/MIME by someone else, signature is valid, the other party sent an attachment with that mail
2. Open E-Mail

OBSERVED RESULT
See that no attachment is listed, neither in plain text nor HTML mode. But the mail is big enough to contain an attachment and Thunderbird (after changing to HTML mode, read additional information) can recognize the attachment in the exact same mail.

EXPECTED RESULT
See the attachment.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian GNU/Linux testing/unstable
(available in About System)
KDE Plasma Version: 5.27.2
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION
My KMail is configured to normally display all mails in their plain text version. Thunderbird had a very similar bug with the exact same mail, but the attachment became visible on Thunderbird after changing the display mode to HTML. Using the banner on the left of the mail to change to HTML mode on KMail did not fix it there.

A representative version of the mail after manual decryption of the S/MIME encrypted content (only the "Content-*" headers) as attached as text file. Comments and replaced content are marked with `[[ ]]`. The number of blank lines in between the contents are correct.