Version: 1.13.2 (using 4.4.2 (KDE 4.4.2), Kubuntu packages) Compiler: cc OS: Linux (i686) release 2.6.32-22-generic When using KMail in Gnome, the To field does not get auto-completed (when entering part of a contact). To enable auto-completion I have to manually open the address book once and then change the entered part of the email/contact to trigger the completion. Once auto-completion got triggered, it works when composing new emails as expected. This might be related to some service not getting started automatically in Gnome, but in KDE.
It's not required to open the address book, but going back and forth to another field in the message compositing window works around this, too.
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.