User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0 Build ID: 20160502172042 Steps to reproduce: I made a mail template (in Dutch: Sjabloon) on Thunderbird an I checked the Read report option (in Dutch: leesbevestiging). Then I safed the message. Actual results: After reopening it, the option is not checked anymore. Expected results: The options should be checked and safed to the template. In Windows 7 this works, in Windows 10 it doesn't.
(The OS won't make any difference. The difference must be in your Thunderbird profiles.) Does it behave differently if you start Thunderbird in safe mode? https://support.mozilla.org/en-US/kb/safe-mode I tested current nightly build for an imap and local account and found no problem