Nowadays (Kmail on SC 4.11.3), it is possible to set the order for contact auto-completion in the Kmail config settings (in section Editor -- translated from French, but I should think this is the name in English). However, I think that contact auto-completion should be moved to identity configuration. I would think that for people having different contacts folder (say CardDAV folders), their first choice of contacts would depend on the identity sending the e-mail. For example, if I have 2 identity (personal/professional) and 2 contacts folders (again personal/professional), it would make sense to always prefer the first folder when using the first identity and so on. Reproducible: Always
Just re-read my comments above, and noticed I forgot to say "Hi !", "Thanks" and "By the way, nice work on Kmail !" ;) Don't like brutal "bug" reports...