Steps to reproduce:

I received a message with an pgp encrypted part. In the previous version 91.8.0 I could open the encrypted part a new window and see the message, like it was mentioned at the end "This is an encrypted part of the message. You need to open it in a separate window by clicking on the attachment". In version 91.9.0 this hin is still there but I can't clock on anything anymore because the attachment is not shown.

Actual results:

No encrypted attachment shown anymore.

Expected results:

Encrypted attachment should be shown.

Does this reproduce with latest?

Possibly related to bug 1763641?

I tested with 91.10.0 and it still shows the same broken behaviour. Last working version is 91.8.0

Are you able to provide a test message?

If you can, please use file save as in thunderbird, which saves as an .eml file, then attach it to this bug.

If you don't want to attach the test message in public, you may send it to me by email. Please don't attach the .eml file directly, to avoid that it gets accidentally corrupted in transit. I suggest to create a zip file that contains the .eml file, and send the zip file to me by email. kaie@kuix.de

Hi Kai,
I've the same problem.

Version: 102.3.0

My colleague and I have created our OpenPGP key from thunderbird. Uploaded them to keys.openpgp.org and added each others public keys to thunderbird.

I have sent a copy of the eml file to your email.

(In reply to keremkoksal from comment #4)

Hi Kai,
I've the same problem.

Version: 102.3.0

My colleague and I have created our OpenPGP key from thunderbird. Uploaded them to keys.openpgp.org and added each others public keys to thunderbird.

I have sent a copy of the eml file to your email.

I've added my gmail account to thunderbird too and tested it between my company and personal emails. I've recreated a new key with RSA-3072 for both of my company accounts. (it was RSA-4096 for my company acount before). I don't think it is a 3072 or 4096 problem.

My company account is hosted on gmail too.

When I send an encrypted mail form personal to company it works fine. But when sending from company to personal, I'm having the problem:
"This is an encrypted message part. You need to open it in a separate window by clicking on the attachment."
But there is no attachment.

Is the server modifying the messages? Check what's sent by comparing the message in sent folder and what's received (ignoring headers).

Bug 1594253?

Sorry, it probably wouldn't be related.

(In reply to Magnus Melin [:mkmelin] from comment #6)

Is the server modifying the messages? Check what's sent by comparing the message in sent folder and what's received (ignoring headers).

Yes. G-suite adds a footnote about privacy. So, the mail becomes semi-encrypted. If I open the mail from gmail, I see the encrypted message as an attachment and I can decrypt it. But thunderbird doesn't show an attachment even though it says "This is an encrypted message part. You need to open it in a separate window by clicking on the attachment."

Please attach a sample email (as .eml) to this bug.

(In reply to Magnus Melin [:mkmelin] from comment #10)

Please attach a sample email (as .eml) to this bug.

Hi Magnus. I've sent an email to you with the eml files for both sent and received state of the encrypted email.

duplicate of bug 1594253 ?

(In reply to Kai Engert (:KaiE:) from comment #12)

duplicate of bug 1594253 ?

no

I am able to reproduce what you see.
The reason was the change from bug 1749340.

For some other messages, our old code caused a confusing display of additional attachments.
However, in your scenario, it has the effect to no longer show any attachment at all.

If I locally revert the change from bug 1749340, and then I use a test message that I can decrypt, I get the original behavior (which you see with Thunderbird 91.8.0).

I will try to find a fix.

I think we should NOT revert the patch from bug 1749340. I don't want to re-introduce the former confusing display.

We should remove the misleading display string "This is an encrypted message part. You need to open it in a separate window by clicking on the attachment."

For all message parts that we don't decrypt, we should make them available, at least (a) shown as a regular file attachment, or (b) as described in bug 1746579.

Doing (b) will be more work, because it requires designing and implementing a UI.

I cannot immediately see a quick way to implement (a).
I will need to take a deeper look at the existing MIME processing code, to find out how to do (a).

Maybe the following strategy to implement (a) could work:

In our code the processes a PGP MIME type (e.g. MimeEncryptedPgpClassInitialize), check what MIME nesting level we're at.

If we decide we don't want to decrypt at this level, call the code that processes regular binary attachments.

The latest work-in-progress patch in bug 1746579 fixes this scenario, too.

Thunderbird Beta version 110 and later contain a fix for this issue. Are you able to test and give feedback if the solution works for you?
If you cannot comment in bugzilla for whatever reason, please send email to kaie@kuix.de
Thanks