Your email attachments may not be as safe as you think they are.
When a you open an attachment from a Time Matters Email, Time Matters has to extract it. Time Matters has to save it somewhere, just like Outlook does, so the file can be opened and displayed.
Time Matters uses the folder C:\Users\USERNAME\AppData\Local\Temp\LNTPA for saving copies of attachments. This is true for attachments to Emails in the TM Inbox, in the Email List and the Email tabs of Matters. MS Windows does not automatically clear out temp folders, so the files build up there and need to be deleted manually.
Typically email attachments are not, or should not be, very sensitive. They travel across the Internet unencrypted and are exposed to interception. But that does not keep people from sending attachments containing confidential information and passwords.
If you open sensitive attachments, it is a good idea to clear out your Windows temp folders periodically. A program like CCleaner can be scheduled to do that automatically.