PGP encrypted sent messages aren't showed decrypted in sent folder (default security settings)

Have you told Evolution to also encrypt using your public key?

Andreas, I sent an encrypted email to a user with his public key (not with mine).

If the mail is only encrypted using your recipient's public key it is only natural that he is the only one who is able to read it. After all, you don't have access to his private key, do you? :-)

If you go into Evolution's Account editor and the tab Security you'll find the option "Always encrypt to myself when sending encrypted messages". That way your public key will always be used.

Andreas, I have been a kmail user for a long time and with this app if you sent an encrypted email to a user and then you want to read it from the sent mail folder you can do this and I think it's a logical thing as it's I that wrote the email and it's not important if I haven't the private key (obviously) of the recipient user. If you encrypt all the email that you send you are in the situation that you cannot read them anymore, but it's absurd as it's you that wrote them.

I add a particular to you: in kde you can read it, from sent mail forlder, the encrypted emails after having typed your own keyring secret key (and I think this behavior it's right).

I then take it you think that the option "Always encrypt to myself when sending encrypted messages" (Account editor / Security) should be enabled by default? That this bug report specifically is about Evolution having a faulty default setting?

Andreas, I think you are right. I tested the option "Always encrypt to myself when sending encrypted messages"and it seems that solve the issue.
At this point, as you sayd, I think Evolution has a faulty default setting as I think a normal user expects he can read all his sent email.

I guess I can confirm this being a bug about faulty, or at least suboptimal, defaults.

could somebody send the request to change the default on bugzilla.gnome.org?

This bug was fixed in the package evolution - 2.32.0-0ubuntu1

---------------
evolution (2.32.0-0ubuntu1) natty; urgency=low

  * Upstream release 2.32.0
    - Empty reply quotation for HTML messages (LP: #630566, #659513)
    - "Encrypt to self" by default on newly created mail (LP: #326979)
    - Backup settings uses unhelpful yes/no dialog (LP: #572985)
    - Can't drag email addresses to Contact List Editor (LP: #282530)
    - Contact List Editor calls wrong EDestination function (LP: #229187)
    - Allow normal, non-vFolder, Trash and Junk folder (LP: #13983, #64762)
      (LP: #135485, #280325, #365270)
    - Allow change of signature hash algorithm (LP: #381290, #381295, #635937)
    - Dialog for mark-all-read always mentions subfolders (LP: #608462)
    - Evolution allows deletion of default views (LP: #498040)
    - Add checks for event->comp_data != NULL (LP: #466415, #546952)
    - Properly free unused message infos periodically (LP: #507972)
    - Calendar compressed weekend print improvement (LP: #88926)
    - Attachment bar causes drawing issues in RTL locales (LP: #545459)
    - [PST] evolution crashed with SIGSEGV (LP: #471852)
    - Swap "Save" and "Save as Draft" accelerators in composer (LP: #424416)
    - Evolution hangs when formatting message - fixes part of it (LP: #175233)
      (LP: #327775)
    - Calendar Day view All Day events print improvements (LP: #88926)
    - Crash on a changed mail filter action removal (LP: #452921)
    - Do not block UI with publish-calendar messages (LP: #594289)
    - Duplicate mnemonic in meeting window (LP: #499418)
    - Hide variable used only with HAVE_LIBNOTIFY (LP: #594289)
  * debian/patches/02_fix_missing_include_for_composer.patch: refreshed
  * debian/patches/03_lpi.patch: refreshed
  * debian/patches/12_remove_not_recommended_for_top_posting.patch: updated.
    The "recommended" text is now a separate label, so removing that object
    entirely.
  * debian/patches/89_express.patch: dropped, applied upstream.
  * debian/patches/90_disable_deprecation_warning.patch: refreshed
  * debian/patches/91_add_u1_email_translations.patch: refreshed
  * debian/patches/91_git_additional_chinese_translations.patch: dropped
  * debian/patches/91_git_fix_e_shell_ref_counting.patch: dropped
  * debian/patches/91_git_fix_untranslatable_list_editor.patch: dropped
  * debian/patches/92_git_fix_proxy_ignore_hosts.patch: dropped
  * debian/patches/92_git_only_hide_signature_on_express.patch: dropped
  * debian/control: update Depends/Build-Depends of all e-d-s parts to 2.32
  * debian/control: libgdata was split out of e-d-s, so updating Build-Depends
    to use the external libgdata library.
  * debian/control: bump libgtkhtml Build-Depends to >= 1:3.31.90
  * debian/*.install: install plugins to /usr/lib/evolution/2.32, not 2.30
  * debian/rules: remove --disable-pilot-conduits, it's not a valid configure
    switch anymore
  * debian/evolution-dev.install: no longer install libeconduit.so
  * debian/control: update Build-Depends with new and updated requirements for
    2.32: adding libpango1.0-dev, libgail-dev, updating libglib2.0-dev,
    libgtk2.0-dev, gnome-icon-theme and libunique-dev
  *...