This might be old hat to the computer whiz kids here. There
is a add on for Firefox and Thunderbird that regulates font size.
Theme Font & Size Changer
The subject lines for Usenet posts were uncomfortable to read.
The size changer fixed that. I couldn't find anything in
Thunderbird preferences to fix that.

On 6/12/2016 7:20 AM, Dean Hoffman wrote:
This might be old hat to the computer whiz kids here. There
is a add on for Firefox and Thunderbird that regulates font size.
Theme Font & Size Changer
The subject lines for Usenet posts were uncomfortable to read.
The size changer fixed that. I couldn't find anything in
Thunderbird preferences to fix that.

Useful ad on which I have.

Think it has been discussed in news.mozilla.org.

I often go there for help after exhausting my personal search.

I download Thunderbird, Firefox and general groups. Helpful folks there.

On Sun, 12 Jun 2016 06:20:40 -0500, Dean Hoffman
wrote:

This might be old hat to the computer whiz kids here. There
is a add on for Firefox and Thunderbird that regulates font size.
Theme Font & Size Changer
The subject lines for Usenet posts were uncomfortable to read.
The size changer fixed that. I couldn't find anything in
Thunderbird preferences to fix that.

Windows (7) has a "Magnifier" utility. I put the Icon on the task
bar. Great for expanding things so you can read them (old hand
written recipes).