User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0 Build ID: 20161129173726 Steps to reproduce: Wanted to tell the 'Smart Reply' button to always honor an explicit 'Reply-To' over 'Reply-To-List'. Actual results: Noted there is no way to customize the behavior of the 'Smart Reply' button. Expected results: There should be a way to perform some minimal customization of the 'Smart Reply' button behavior to make it 'smarter'. To elaborate, with only a few small tweaks, the 'Smart Reply' button could be made smart enough to completely replace the simple 'Reply ' button (and consequently should be available on all toolbars, not just the Message Pane Header toolbar - see bug 868961). By tweaks, I specifically mean: 1. Keep it's current auto-detection of List-Post headers that allows it to switch to 'Reply List' instead of just 'Reply', as well as the select/drop-down selector/arrow to choose an alternate Reply type, 2. There should be an option how to deal with a Reply-To header when it is explicitly set. Of course, how this option is presented would depend on what is decided on as the default behavior. Ie: If it is decided that the default behavior should be to 'always honor an explicit Reply-To' - and I personally believe that this should be the default - then provide an option to 'allow Reply-To-List to override an explicit 'Reply-To' header'. But, if the default behavior is to 'allow Reply-To-List to override Reply-To when explicitly set', then the option should be to 'always honor Reply-To when explicitly set'. Note: making the above a global config option would be ok with me, but I can see an argument for making it per account/identity, but this could be handled with a follow-up bug. Now, for the alternate Reply methods available when clicking the selector/drop-down selector/arrow... 3. When List-Post header *is* present: a) change the label/function for the plain 'Reply' alternate method to 'Reply ignoring Reply-To header' (this is what currently exists for messages without List-Post headers), and b) keep the current 'Reply All' label for replying to all, 4. When List-Post header is *not* present, there are currently too many choices - these should be whittled down as follows: a) Make the default behavior to reply in the current format (ie, plain text for plain text messages, HTML for HTML messages), and remove the choices for replying in the same format from the list of alternate methods (there are two), b) Make the default behavior be to honor an explicit Reply-To header when present (I think this is current behavior?), and c) Keep the existing 'Reply ignoring Reply-To header' alternate reply method and last, 5. Make it clear that when configuring the 'Smart Reply' button, all you are doing is changing it's default state and label - ie, the text/label displayed on the button and what will happen when the button (not the select/drop-down selector/arrow) is simply clicked. The alternate reply methods would still be available when clicking the select/drop-down selector/arrow.

(Ignoring munged reply-to was bug 77304)

Thanks Melin - but I don't see the relevance of your comment. This bug isn't about Reply-To munging (ignoring or otherwise). One aspect of it is about always honoring the Reply-To header, but that is just one aspect. It is really about - as the summary says - making the 'Smart Reply' much smarter, and more flexible, than it currently is. In fact, I found another old bug that has an excellent set of examples of how Replies should be done, and will be posting a follow-up here later today, or more likely in the morning (when I have more time).

Still working on a detailed clarification of this bug...

> replace the simple 'Reply' button with it Along the same line, we should be able to bind "smart reply" to shortcut "Ctrl-R" (instead of the default reply command).