Hi! Please update to 15.08 in lockstep for kdepim and akonadi packages.
If you upgrade to akonadi 15.08 before installing kdepim 15.08 your kdepim 4.14 will be inoperable. Thats the switch to Qt5 based akonadi and kdepim. Qt4 based KDEPIM cannot talk to Qt5 based Akonadi. If you already upgraded, wait till kdepim 15.08 packages appear and use a different mail client for the time being. I saw Akonadi 15.08 and kdepim 15.08 coming through to unstable today, so just take care to wait till all of them are built before upgrading. Same applies if you use testing. Thanks, -- Martin