back with this bug with KDE 3.5.7 ; I tried to delete the configuration file in ~/.kde setting : it worked at the next opening of the application but then falled beack into the buggy behaviour as decribed above ! 

*** Bug 146684 has been marked as a duplicate of this bug. ***

Could someone who experiment this issue paste the content of the "[IDENTITY]" block from its knode configuration file (~/.kde/share/config/knoderc) ?

Bonsoir Olivier,

Please find below the relevant section of my ~/.kde4/share/config/knoderc.
Yes this applies to knode Version 0.99.01 using KDE 4.1.3 (KDE 4.1.3) "release 69.6", openSUSE 11.0 x86_64 RPM packages from STABLE repository.

[IDENTITY]
Email=hendric.stattmenn.2009-01@kabsi.at
Mail-Copies-To=                         
Name=Hendric Stattmann                  
Org=                                    
Reply-To=hendric.stattmenn.2009-01@kabsi.at
SigningKey=689438B1                        
UseSigFile=true                            
UseSigGenerator=false                      
sigFile[$e]=$HOME/.signature               
sigText=                           

SVN commit 919671 by otrichet:

More debug output for #138821 (fails to attach a signature to messages)
CCBUG: 138821


 M  +9 -2      knconfig.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=919671

Seems to be gone in 1.12.0 (KDE 4.3). You may close this one. Thank you!
Hendric

SVN commit 1075588 by otrichet:

Convert KNode's identity to KPIMIdentities::Identity

 - Convertion code run once at startup (should be able to run multiple
   without much breakage).
 - New identity selection widget
 - New identity edition dialog
 - Porting

This should make selection and edition of identity a bit more clear.
The same identity can be used for multiple groups.
Bug related to loading of identity content magically disappears.

BUG: 147471
BUG: 143291
BUG: 107072
BUG: 23622
BUG: 138821

RELEASE: 4.5

 M  +20 -7     CMakeLists.txt  
 A             configuration (directory)  
 A             configuration/identity_combo_wrapper.h   [License: MIT]
 A             configuration/identity_edition_dialog.cpp   [License: MIT]
 A             configuration/identity_edition_dialog.h   [License: MIT]
 A             configuration/identity_edition_dialog.ui  
 A             configuration/identity_widget.cpp   [License: MIT]
 A             configuration/identity_widget.h   [License: MIT]
 A             configuration/identity_widget.ui  
 A             configuration/settings_container_interface.h   [License: MIT]
 M  +1 -1      knaccountmanager.cpp  
 M  +50 -100   knarticlefactory.cpp  
 M  +2 -2      knarticlefactory.h  
 M  +2 -2      kncleanup.cpp  
 M  +1 -1      kncollection.h  
 M  +22 -15    kncomposer.cpp  
 M  +27 -15    kncomposer.h  
 M  +4 -159    knconfig.cpp  
 M  +1 -83     knconfig.h  
 M  +2 -5      knconfigmanager.cpp  
 M  +0 -3      knconfigmanager.h  
 M  +6 -13     knconfigpages.cpp  
 M  +5 -255    knconfigwidgets.cpp  
 M  +2 -62     knconfigwidgets.h  
 M  +1 -1      knfolder.cpp  
 M  +1 -1      knfolder.h  
 M  +2 -2      knfoldermanager.cpp  
 M  +16 -5     knglobals.cpp  
 M  +7 -0      knglobals.h  
 M  +17 -35    kngroup.cpp  
 M  +23 -10    kngroup.h  
 M  +3 -3      kngroupmanager.cpp  
 M  +2 -1      kngrouppropdlg.cpp  
 M  +1 -14     knmainwidget.cpp  
 M  +33 -37    knnntpaccount.cpp  
 M  +27 -11    knnntpaccount.h  
 M  +8 -0      knode.kcfg  
 M  +4 -1      knode_part.cpp  
 M  +22 -16    knstringfilter.cpp  
 M  +1 -1      knstringfilter.h  
 M  +3 -1      main.cpp  
 M  +16 -2     settings.cpp  
 M  +22 -2     settings.h  
 M  +158 -2    utils/startup.cpp  
 M  +23 -2     utils/startup.h  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1075588