Tested with VS-Desktop-3.3.90.8-Beta and the test gpgol.dll from 2025-09-10 and the same test mail from the original report:
The spawning cycle does not occur any more. (Tested with Outlook setting "show as text only" and without.)

Still the same behavior as described in https://dev.gnupg.org/T7240#202915 on gpg4win-5.0.0-beta369 @ win10

Here are the messages and logs, when trying to open them:

Andre mentioned in 10721b1dccf4 that "Closing the mail this early might also have contributed to
endless loops of read + close" which is what we see here as well

How to test this? The follwing happens for an attachment of an encrypted mail on gpg4win-5.0.0-beta357, Outlook LTSC Standard 2024 @ win10:

Moving an encrypted message on Gpg4win-5.0.0-beta357, Outlook LTSC Standard 2024 @ win10 into an inbox subfolder of Ted.Tester and back works for me, too. Does this confirm, that it's working now?

Note that disabling Auto-preview is not the default and has only been implemented to work around severe performance degradation with certain MalwareAnti-Virus software.

I think it is save to say that we will not implement pgp/inline encryption with attachments

The culprit seems to be commit rO6cb4ccf4d8db03e9922984d9c5f5bf7f8806954d but a brief inspection does not show any problematic code. Thus this might be due to an Outlook peculiarity.

The reporter in the forum originally wrote:

We have no solution right now.

In short: A message was saved as an encrypted draft and then the user edited that draft, disabled encryption and then the message was sent out only encrypted to the draft key.

Deselect email and select again (email gets decrypted again) attachments are back.

We should not modify the HTML at all but display it as plain text. Maybe put a a notice at the top:

<!-- Below is the raw HTML encoding of this mail - ask you admin for advice -->

We won't implement that any time soon given that gpgol2 will be an easier plaform to get it right.

It is unlikely that we will fix it. The OL behaviour is just too flaky. It might be possible to do this in the no-preview mode in a more robust way.

I could not reproduce this issue with Gpg4win 4.4.1 and did not see it with Gpg4win-5.0.0-beta345, either.

I could not reproduce this issue with Gpg4win 4.4.1 (which should have it).

tested with Gpg4win 5.0Beta-336

This one made me curious because updating the should be UI solved, and it is incredibly dangerous to mess with that. It is super easy to get random crashes when you invalidate the UI too much. It took me ages to get that "stable enough". But also technically an appointment request is a mail. And thanks to dan (afair), KMail can sign and encrypt invitations. And at least for signed invitations they are displayed as appointment so I looked into this a bit out of curiousity.

In T4836#132493, @aheinecke wrote:

Thank you for the detailed report.

We recently had a similar problem with S/MIME Mails. T4543 I think that we can apply the same fix we did for S/MIME also for OpenPGP. So I give this high priority as I think that this can be easily fixed and is a big problem in mixed environments.

was fixed in gpgol 2.5.15

Test with KF6 (open, close, open config dialog).

see T7098

Outlook problem that can't be fixed.
Workaround possible (First start message, then add recipients).

Fixed in most cases.
Edge cases will be examined further.

I suspect there's also a bug somewhere between qt and windows involved here: The overlay is supposed to be modal to the composer window, so it shouldn't be possible to move the overlay behind the compositor. This is probably the reason why the overlay is forced to stay on top in the first place...

Well it kind of works but it is a bit ugly and the encoding in the "Encrypt" message is broken:

An easy solution seems to be to just tell the overlay to not be always on top. It still blocks the outlook window, but other windows can then be shown on top of it.

Fixed:

turned out that not the flowcrypt encryption is the issue here. The cause seems to be the usage of Proofpoint "Email Warning Tags".

Gpg4win is a community version and we may or may not apply Authenticode signatures. You can do that yourself, after having checked our OpenPGP release signature. You may however be interested in GnuPG Desktop, which comes with full support and also Authenticode signature.

Forgot a screenshot:

Yes. I did only one test though, with an inline PGP mail sent with Claws.

Yes it does. I even tested it yesterday.

Looks like plain old inline PGP. Does GpgOL even support inline PGP?

https://flowcrypt.com/
They use OpenPGP.js according to https://flowcrypt.com/docs/getting-started/overview/openpgp-compatibility.html
They have a cooperation with Google.