I fixed the problem (which I identified above) in gniibe/t7759 branch. There might be other causes/problems for the particular symptom, so, I don't know the fix resolves the symptom or not, though. Anyhow, I believe that this is an improvement.

re 1: Only if the option --auto-key-upload is used/configured.
re 2: Do not configure --auto-key-upload but give it on the command line.
re 3: Do not use --auto-key-upload - maybe I should add a --no-auto-key-upload option.

Hi
I have some questions about the "auto-key-upload: If an LDAP keyserver is configured (in dirmngr), upload a newly created key directly to that server" feature:

1. If an LDAP keyserver is configured, will every newly created key be uploaded? Is this upload behavior enabled by default?
2. Even with an LDAP keyserver configured, what if we don’t want to upload by default? If we prefer manual approval or want to upload only a specific subkey, how should we handle that?
3. What about keys created for testing, temporary use, or personal privacy-sensitive purposes that we don’t want others to discover?

People who use GPG tend to care deeply about privacy and don’t want to upload or expose unnecessary information.

Especially when an LDAP is configured, keys should be automatically refreshed in short intervals (5 days? Configurable?) to notify users about revoked keys or signatures from a trusted key.
Keys that are close to their expiration dates should be prioritized.
Maybe users want to configure for what mail domains a lookup on a configured LDAP should be done.

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

@gniibe: Now that we use the KEM API, how do we proceed with this ticket?

The problem here is that we don't have the sha-2 fingerprint in our SQL tables. Thus we would not only need to do a full table search but also parse the actual blob to compute the sha-2 fingerprint.

We should change the key binding time from the ADSK creation time to the current time or the time the other self-signatures use.

tooltip suggestion for d, not trusted and expired:
Ask the sender for an updated certificate and when you receive it, follow the procedure to establish trust and certify it.
or:
Ask the sender for an updated certificate. When you receive it, you need to establish trust and certify it.

I have done testing using my QES certificate with all combinations of the two options.

Thank you for the report.

Similar situation could happen with gpgsm + gpg-agent, when gpg-agent is invoked by gpgsm.
(1) No gpg-agent.
(2) In gpgme, by engine-gpgsm, gpgsm is invoked with --logger.
(3) In gpgsm_keylist, it makes sure gpg-agent is available by GETINFO agent-check, using gpgsm_assuan_simple_command.
(4) In the server side, it tries to connect gpg-agent, invokes gpg-agent, and connect to the agent again.
(5) On Windows, it may takes time to invoke gpg-agent. And it may try to connect multiple times. Each trial may generate debug messages.
(6) When it takes too much time, the debug messages are too much. It may fill the pipe.
(7) And it blocks at log_string in my_libassuan_log_handler.
(8) ... it hangs.

Hypothetical scenario (gpgsm --server + dirmngr):
(0) It may hang when much debug messages are generated by libassuan to the pipe of --logger (diag_cb).
(1) In gpgme, by engine-gpgsm, gpgsm is invoked with --logger.
(2) If it's the case of standard gpgme interactions which uses gpgsm_io_event, no problem. Because the data on diag_cb is consumed well.
(3) In case of gpgsm_encrypt (or other commands), it uses gpgsm_assuan_simple_command which does not consume the data on diag_cb pipe at all.
(4) In particular, in set_recipients, gpgsm_assuan_simple_command is called by the number of recipients times.
(5) IIUC, in the server side, to handle RECIPIENT command, dirmngr is used by the call chain of:

• cmd_recipient
• gpgsm_add_to_certlist
• gpgsm_validate_chain...
• gpgsm_dirmngr_isvalid

(6) In gpgsm_dirmngr_isvalid function, libassuan is used as client side, it generates debug messages.
(7) When there are many recipients, the debug message may be big enough to fill the pipe.
(8) When pipe is filled, it blocks at log_string in my_libassuan_log_handler, waiting the data in pipe is consumed.
(9) ... it hangs.

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.