This issue is really caused by the Mail (SMTP) server and its own formatting of HTML, however you are able to force TaskCentre to use a specific HTML character set which should help.
First, you will need to add a registry key to the server where TaskCentre is installed. This should only be done by someone with the required authority and by someone who is familiar with the registry - any issues where a mistake has been made will not be covered by Support.
Log onto the server where TaskCentre is installed
Click on Start and in the Search box or Run box, type "regedit" and press Enter
If prompted by User Account Control, click Yes to open the Registry Editor
In the Registry Editor, navigate toHKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Orbis Software\TaskCentre\Providers\{6441D52B-BABE-4A69-A21F-A5ED9B62FAAC}\Parameters
Right click in the right hand panel and select New, String Value
Name this new key "CharSet" and press Enter
Right click on the newly created key and select Modify...
Set the Value data to "UTF-8"
Click OK to save the changes - the key has now been added
Test your emails again and see if this has helped - if it has not, you may need to try changing the value of the registry key to another character set. We recommend trying the following until you find which one suits your set up:
Windows-1252
ISO 8859-1
us-ascii