I just saw that the new KPA mailing list currently invalidates originally added DKIM signatures by prepending "[KPhotoAlbum]" to the subject and appending > -- > Kphotoalbum mailing list > Kphotoalbum at kde.org > https://mail.kde.org/cgi-bin/mailman/listinfo/kphotoalbum to the original message. I hope I could fix this now in the settings. Let's see ;-)