Yes I'm afraid my solution previously was based on the assumption that this was being used for web reproduction as clearly did not read the query. I think seeing all those <br />'s sidetracked me.
I have tried a few different variations of writing the html. I even got to some very unorthodox coding solutions but the problem is not the code or carriage returns being erroneously input into the files when the composer saves the signature. (The preview is fine it's just when the signature is written to file)
I think the problem is one of scale - when you switch between the text and html modes the resolution for the html mode seems to drop resulting in a large rendering of html.
There are possible workarounds I can see.
1. add a script to generate the signature - problem being what script, language and what peramaters are to be used?
2. create an image file which you can then add in to the HTML mode of the signature maker. The only drawback with this is if the recipient does not access images via their e-mail.
3. Use the text mode.
here's some useless pre code which tried out.
It may be worth submitting a bug report via the help drop-down - after seeing if this is a known problem at the project site first of course. It looks as though there's a lot of general updating and fixes going on so it may be that this is under their attention already.
<pre><font size="3" face="verdana, sans-serif" color="#800000">
<font size="4" face="verdana, sans-serif" color="#800000"><b>
Knapp Drafting & Design</b></font>
<font size="2" face="verdana, sans-serif" color="#800000">
14450 N North Point Court
Columbia, Missouri 65202
Office 573 442 6603
Cell 573 999 9317