#718 Sent Items message "Decryption Incomplete": Linux and Windows

[Craig Arno]

Under both Linux (Ubuntu 16.04 LTS x64) and Windows 10 Pro both Thunderbird 52.4.0/Enigmail 1.9.8.3 when I send a PGP/MIME encrypted and signed message containg one 60K attachment and many pictures, the copy saved in the "Sent Items" folder is not readable. i.e. I can't read the message I sent. The recipient tells me the message decrypts using Enigmail on the receiving end. The only issue is I can't see what is sent in the Sent Items folder.

I attached a copy of the "Sent Message" contents copied into a LibreOffice Writer document before sending. Subsequent attempts to send were copied (CNTL-A CNTL-C) from this document and pasted (CNTL-A CNTL-V) into the message body and sent using PGP/MIME with encryption and signature. FYI, "Problem #1 second paragraph of this report is incorrect, the problem shows the same in both Linux and Windows Thunderbird/Enigmail installations. I also emptied my Sent Items folder to see if size was the problem. Folder size was not the issue.

The exact message I see when I try to view the Sent message is "Decryption incomplete; Click on 'Details' button for more information" Of course when I press the details button all I see is a dialog which says, "Enigmail Alert, Enigmail Security Info, Decryption incomplete, OK"

The original message is about Thunderbird Linux memory usage, and I want encryption because there is multiple account information security details contained in the data I'm sending with this report.

GPG info:

# gpg --version
gpg (GnuPG) 1.4.20
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: ~/.gnupg
Supported algorithms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
        CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

C:\Users\craig>gpg --version
gpg (GnuPG) 2.0.29 (Gpg4win 2.3.0)
libgcrypt 1.6.4
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: C:/Users/craig/AppData/Roaming/gnupg
Supported algorithms:
Pubkey: RSA, RSA, RSA, ELG, DSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
        CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

[Craig Arno]

Don't know if it will help, but I'm including the Sent Items folder with the result of my send attempts. This is the folder and messages causing the "Decryption incomplete" message. There are three message send attempts.

[Ludwig Hügelschäfer]

Craig, thanks for the report. I have tried to decrypt the Mails in "Sent Items", but I haven't got the right private key(s). So maybe this conceals the problem.

May I suggest that you create an "Execution Trace" (instructions here: https://enigmail.net/index.php/en/faq?view=topic&id=15#faqLink_6).

You may also try a nightly build of Enigmail and test if this bug has been fixed already. https://www.enigmail.net/index.php/en/download/nightly-build

[Craig Arno]

Debug Execution Trace Log attached.

[Craig Arno]

Installed nightly.
Repeated experiment.
Result - Decryption incomplete
20171118nightly debug event trace log file attached

[Patrick Brunschwig]

The reason for this behavior is a Thunderbird "feature":

If the option "Only download attachments when opened" is on, AND the Sent Items folder is not enabled for offline use, AND the global search index database is disabled, then Thunderbird will only load the first 40 KB of a message, which renders Enigmail unable to decrypt the message.

You have two main options:
1. change one of the above mentioned settings (I recommend the 1st one)
2. Use the menu Enigmail > Reload Message (this will ask Thunderbird to reload the message in its entirety).

Either solution requires you to enable the expert settings in the Enigmail preferences. The option "Only download attachments when opened" is found in the "Advanced" tab of the Enigmail preferences; you have to DISable the option.

[Craig Arno]

I may be missing something in this conversation. I think what you are referring to is "Synchronization & Storage", see attached image file for my settings which haven't changed since the start of this conversation. I looked through account settings and Thunderbird preferences and can't find anything else which might match. Where is "Only download attachments when opened" set, if not here? Is there an "about:config"? I checked Troublshooting Information and didn't see anything obvious to change.

Otherwise, I agree, what you describe does sound like it fits, I just can't find the specific setting.

[Craig Arno]

Never mind, messages are now showing up which previously indicated "Decryption incomplete". I don't think I changed anything, but it's working now and I'm still scratching my head to figure out what changed. All I did was look at settings. I didn't change anything.

[Patrick Brunschwig]

"Only download attachments when opened" is set in the Enigmail Preferences in the Advanced tab.

That's accessible via Menu Enigmail > Preferences. If you don't see the "Advanced" tab, click on the button "Display Expert Settings and Menus".

The global Synchronization & Storage settings can be overwritten for each folder: right-click on the folder > Properties > Storage.