Since yesterday evening the openSUSE KDE4:Unstable repositories contains the KDE SC 4.5 rc1 packages. Also the special repository that contains KDEPIM 4.5 snapshots, was updated to a version that seems to work pretty well.
I am not using IMAP, so I can’t comment on it’s status. But the POP accounts are working very well and also filtering is active. At least it allowed me to move away again from Thunderbird to this Kmail v2 solution. A very good job done by the KDEPIM developers!!
If you could be so kind as to check how IMAP functions after resuming from suspend I might be inclined to upgrade to RC1. Right now KMail is virtually unusuable if you ever suspend (to RAM or disk) your computer.
I am very sorry, but I won’t be able to validate this for you. I am running kdepim v4.5 svn and KDE 4.5 SC RC1 is shipped with the kdepim modules from 4.4. I guess the best way is to validate your issue in the #opensuse-kde channel on IRC.