To clarify, this is *not* about KDEPIM 4.7 - the fact that the original report has KMail 4.4.10 proves that. I can confirm that I've also experienced this issue when upgrading to KDE 4.7 via the backports PPA, which does not contain the new KDEPIM; one can only assume that one of the libraries it uses has some kind of bug or incompatibility with the older KDEPIM that is the root cause of this issue.
To clarify, this is *not* about KDEPIM 4.7 - the fact that the original report has KMail 4.4.10 proves that. I can confirm that I've also experienced this issue when upgrading to KDE 4.7 via the backports PPA, which does not contain the new KDEPIM; one can only assume that one of the libraries it uses has some kind of bug or incompatibility with the older KDEPIM that is the root cause of this issue.