You should see a small band of white before the first letter, unless you choose (or you are replying to) an email template that eliminates that normal margin.

If you want to manually enlarge that left margin, you can use:

Format > Page Colors and Background > "Advanced Edit" button

In the Advanced Property Editor, click the "Inline Style" tab

Under Property, type or paste:

margin-left

In value, type or paste the amount you want to use. For example:

3em

An "em" is the standard line height, so for a font size of 16px this creates a margin of 48px, or about half an inch. If you prefer, you can use:

0.5in

For half an inch (so that is fixed regardless of the font size of the message).

This was the first thing I discovered, so it wouldn't surprise me if there is an easier way.

Oh wait: use the toolbar buttons just above the compose box. In the section with bullets and numbering, the fourth icon will indent paragraphs, and the first button in the next section sets the alignment.

Hello there and thanks for your swift response - I saw your "Oh wait" comment just as I was about to say "didn't work" !!! but it does, using that 4th icon you mentioned. I wonder if there's a way of making this margin indent the default ???

Many thanks again

Graham (Ely, Cambs, UK)

There is an add-on that allows you to create a custom template or stationery for Thunderbird messages. I haven't tried it myself, but it might allow you to set an indent as well as changing the alignment.

https://addons.mozilla.org/thunderbird/addon/stationery/

Windows wont download the stationery template I'm afraid ("not recognised")

http://chrisramsden.vfast.co.uk/3_How_to_install_Add-ons_in_Thunderbird.html

Thanks for your interest but Windows isn't allowing me to install add-ons - god knows why !!!

Graham

I don't have Thunderbird on this computer, but there is a way to "get add-ons" from inside Thunderbird that probably would work better.

…there is a way to "get add-ons" from inside Thunderbird that probably would work better…

http://www.ramsden.org.uk/3_How_to_install_Add-ons_in_Thunderbird.html

…Windows isn't allowing me to install add-ons…

What error, warning, message or event leads you to say that?