It's unclear how to fix this, since it would need at least decoupling the decryption from signature verification, which doesn't appear to be so easy to do with just gpg - I couldn't figure it out. There's still a bug open upstream though, so my suggestion would be to add as much debugging information to that bug report so that someone can look into the issue and try to fix it.
Note that there are already possible workarounds. One of which being to manually download the public key for the user sending the email; since the error will only show up if an encrypted email is sent and no public key is available. It's also possible to send emails in different formats (not pgp-mime) which will allow evolution to display the email properly. To manually download public keys, you can start "seahorse" (the Passwords and encryption keys application, search for keys by name or by ID (with the ID provided in the gpg message), then use the import button once the correct key is selected. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to evolution in Ubuntu. https://bugs.launchpad.net/bugs/689271 Title: Evolution fails to decrypt GPG message if signature (not encryption) key is not available Status in The Evolution Mail & Calendaring Tool: New Status in “evolution” package in Ubuntu: Confirmed Bug description: Binary package hint: evolution It seems that the bug https://bugs.launchpad.net/ubuntu/+source/evolution/+bug/90339 has reappeared in evolution 2.30.3-1ubuntu7.1 Actual results: 1) I receive a GPG encrypted mail, sent to my public key. However, the mail is signed with a key not in my keyring. 2) Evolution does not display the mail, instead it displays a red error text output from GPG, with a message that the public key used for the signature was not found. 3) Result: I cannot read the mail using Evolution. However, I am able to read the mail on the command line by using `gpg --decrypt` -- it shows a warning about missing signature key, but also shows the mail body. Expected results: Evolution should show the mail body, plus a broken "seal" at the bottom indicating that the signature public key was not found. Does this happen every time? Yes. ProblemType: Bug DistroRelease: Ubuntu 10.10 Package: evolution 2.30.3-1ubuntu7.1 ProcVersionSignature: Ubuntu 2.6.35-23.41-generic 2.6.35.7 Uname: Linux 2.6.35-23-generic x86_64 NonfreeKernelModules: ath9k nvidia mac80211 ath9k_common ath9k_hw ath cfg80211 compat Architecture: amd64 Date: Sun Dec 12 15:13:56 2010 InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007) ProcEnviron: PATH=(custom, user) LANG=fi_FI.UTF-8 SHELL=/bin/bash SourcePackage: evolution To manage notifications about this bug go to: https://bugs.launchpad.net/evolution/+bug/689271/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

