To repair a damaged PoliteMail client, run the client.exe of the version you have installed. You will find this link in the Welcome email you received from PoliteMail. After clicking this link, choose Run. You will then be brought to the InstallShield Wizard.
From the next window, choose Repair.
On the next window, confirm your installation settings and destination folder. If correct, click Install.
When finished, you get a confirmation window. Click Finish to complete the process.