Version: 1.13.5 (using KDE 4.4.5) OS: Linux There is no checkbox nor other method in KMail config dialogs to set signing with gpg the dafault. Actually one has to click the "Sign message" button each time. Info in http://userbase.kde.org/KMail/PGP_MIME#Setting_up_Kmail_to_sign_emails_using_your_gpg_key is for KDE 3.5's kmail and can not be used in KDE4's kmail. Or, at least, step 6 of it does not say HOW to do that (there is no checkbox or option for that in the identity dialog). Reproducible: Didn't try
Thank you for taking the time to file a bug report. KMail2 was released in 2011, and the entire code base went through significant changes. We are currently in the process of porting to Qt5 and KF5. It is unlikely that these bugs are still valid in KMail2. We welcome you to try out KMail 2 with the KDE 4.14 release and give your feedback.