https://support.countermail.com/kb/faq.php?id=134
 http://kb.mozillazine.org/Minimize_the_size_of_a_profile

Hi, I have a user reporting a problem with Thunderbird that has been happening for ages. Windows 7 Pro SP1, Thunderbird 60.5.3 (32-bit) Addons: Lightning, Secure Addressing, Show Address Only, Torpedo I don't think any of the addons affect composition but I'll ask him to test in safe mode (although he'll be less safe without them, ironically). Composition is in HTML and Thunderbird has been configured to prevent/minimise local storage based on the advice given here: https://support.countermail.com/kb/faq.php?id=134 http://kb.mozillazine.org/Minimize_the_size_of_a_profile The problem is that, with a message being displayed in a pane at the bottom of the window (i.e. it's not being displayed in a separate window), he clicks on the reply button at the top of the window (i.e. not the reply button at the top of the pane that is at the bottom of the window), a new window appears to compose the reply in, but the To: header field is empty (i.e. it does not contain the email address of the sender of the email that is being replied to). His email signature is present, and the attribution of the quoted message is there below it (i.e. the name and time of the replied-to message) but the quote of the original message itself is absent. He also reports that often, when the above happens, and he hasn't noticed until after having composed the reply, he copies his reply into the clipboard, initiates another reply so as to get the To: header and the quotd original message, but pasting his previously written message doesn't work. So either the copy or the paste didn't work. Both of these problems are intermittent and very frustrating as you can imagine. He also reports many crashes some days and some crashes most days but he's submitting creash reports so hopefully that will help.