On the toolbar > Options > Composition > General is where such defaults are set. Are you using those options?

Matt said

On the toolbar > Options > Composition > General is where such defaults are set. Are you using those options?

Thank you for replying.  :) Yes, I am using those options. TB formats my reply text correctly, but also changes the text of the email that I'm responding to. I've attached a sample.

If there is hardcoded html css setting the font colour in the original received email, then this should be preserved and show the original section as intended and your section as you would like, but if there is no hard coded formatting in the original then it will apply whatever default setting you choose to the whole email.

In the past, I've had emails that were created using MS Word which always includes a load of unnecessary coding. When I selected to Reply, I could not control any default font colour or background colour because of the css coding in the original email. Eventually, I manually accessed the email and make alterations in order to Reply using my formatting. I do not suggest you do this. I did it as a one off as did understand what I was doing. But it is an example of how formatting hardcoded into an email can have unexpected effects.

You could use the 'Formatting Bar' to change font colour for that email.

There is an addon, but you may need to alter the install.rdf to cope with newer versions.

• Worth a try.
• https://addons.mozilla.org/en-GB/thunderbird/addon/quote-colors/

Thank you for this information, Toad-Hall. Many of my replies are to emails that people have composed on cell phones, which I'm presuming do not always hard code the font settings.

I've decided to just click the font button on my replies, individually formatting my responses to the emails.

Thanks!