1. I think you're referring to the minimum height or width of the message list, or threads pane. There is a css solution here: https://support.mozilla.org/en-US/questions/1427439

2. Post a picture of exactly what you want. In the attached picture, I have made the sender and subject distinct with css (blue for read, black for unread), and added zebra striping and line separators.

3. Same method as in 2.

4. In webmail, move old mail to a separate folder that is not subscribed in TB.

5. Maybe a picture would be helpful. Do you mean threads in the message list or the conversation in a single received message? For my purposes, View/Sort by is always Unthreaded.

@sfhowes Thank you for your response.

1. I'm a user, not a programmer. The last time I used a programming language was HTML circa 1995. I don't think CSS even existed then--at least not mainstream. I'll take your answer to mean I can't check a box or drag a corner to enlarge the cards. ;)

2. Your photo is very close to what I want. Imagine the same, but bold, black and big for the sender (not bold once read), black (not bold) and smaller for the subject, and a light grey tiny font for the date and time. Definitely want the separators and zebra striping! That helps a lot. Maybe a lighter grey, though. It doesn't need to be an in-your-face color scheme, just a subtle indicator that there's a difference between one block and the next.

4. I've tried that, but they keep bouncing back into the main inbox. I received a newsletter just today at 12:59 ET that I've moved into that client's folder four times, but it keeps coming back to the top of the inbox.

5. A single topic email with a sender, a recipient and a cc recipient all participating. Inbox is set to: Sort by>All Mail>Date>Descending>Threaded. I'll have to revisit this one at a later time, though. When I got back into Thunderbird this afternoon, all messages were visible. (In ascending order, but visible.)

Correction:

1. 4: That newsletter "bounced back to the inbox" because I was in All Mail, not Inbox. That's my fault. Please disregard.

1. 5: Oops! I'm still in All Mail where the thread displays differently than when in Inbox. I can see everything I need in All Mail (although in reverse), but when I switch back to the inbox, I lose those 4 responses I mentioned in my OP. There is client information all over my screen, so I'll have to revisit another time when I can scrub the page before sending a screenshot. For now, please disregard.

1. 2: I'd love to see a Thunderbird update with options similar to what you've created in your image. Programming it for myself will never happen, sadly. I suspect this will be an issue for other folks coming over from Mail, too.

Thanks again for your help! It was a treat to be able to discuss all the issues in a single day. :)

Most users unsubscribe All Mail and delete its file from the profile. See the All Mail section here.

The css modifications don't require any programming on your part, just basic file management that's explained in the link in my first reply. Search the web for thunderbird userChrome.css for other examples.

Here is my css for cards:

/* bold sender in card view */
.thread-card-container :is(.sender){
	font-weight: bold !important;
	color: blue !important;
	font-size: 15px !important;
}

/* unread card sender */
tr[is="thread-card"][data-properties~="unread"] :is(.sender) {
      color: black !important;
      font-weight: bold !important;
      font-size: 15px !important;
   }

/* indent card subject */
.thread-card-subject-container :is(.subject){
	margin-left: 10px !important;
	font-size: 13px !important;
	color: darkred !important;
}

/* unread card subject */
tr[is="thread-card"][data-properties~="unread"] :is(.subject) {
      font-size: 13px !important;
      font-weight: bold !important;
   }

/* selected card bg color */
html|tr[is="thread-card"].selected {
     background-color: lightgreen !important; 
}

/* zebra striping */
#threadTree tr:nth-child(2n) {
  background-image: linear-gradient(rgba(0,0,0,.10), rgba(0,0,0,.10)) !important;  
}

/* threads pane lines*/
table[is="tree-view-table"] td {
     border-bottom: solid 1px blue !important;
}

Thank you so much for this! I did end up here: https://support.mozilla.org/en-US/kb/config-editor, which warns that any changes can compromise Thunderbird security. Because I work with client info, I can't take the risk, but I sincerely appreciate your dedication to helping me (and many other users, it looks like).

If you're in a position to add these types of configuration options to a future Thunderbird update where users like me can make these kinds of changes without compromising warranty, usability, or security, I would be *tremendously* grateful.

Thank you again for your time! People like you make the internet a better place.

You could always use the wide or classic view which places the email content at the bottom of the screen and by default makes the other two columns wider. Personally I use the wide view because it was closest to the outlook express view I was used to when I migrated to Thunderbird and see no reason to change.

You could always use the wide or classic view which places the email content at the bottom of the screen and by default makes the other two columns wider. Personally I use the wide view because it was closest to the outlook express view I was used to when I migrated to Thunderbird and see no reason to change.

Finally getting back to this. How do I find the wide or classic view? I've looked all over the place, but I'm not finding the right spot. (No idea which version of Thunderbird I'm using. This hamburger menu https://support.mozilla.org/en-US/kb/find-what-version-thunderbird-you-are-using does not exist on my screen, so I have no idea where to find that info.)

View/Layout has the options. Press Alt if the Menu Bar with View is hidden. The same choice appears under the hamburger menu. If you don't see the menu, see if it appears in safe/troubleshoot mode (hold Shift when launching TB).