When I want to choose the font for the signature template, I don't see the Calibri font in the dropdown list.
Why is that since it is the default font in Outlook 2007?
Update: January 2014, Calibri is now on the font list. The method below is still a good method for other fonts.
We have chosen not to add this font to the template editor, because it is only present in Outlook. And you must remember that the Microsoft platform is not the only one present on the internet.
The fonts you see in the template editor are fonts that is present on ALL platforms on the internet.
If you were to use the Calibri font, and it is not present on the recipients platform, then the recipient client will chose to display your email in what ever is the default font.
That is most often Times New Roman.
The best approach to using the Calibri is to use font families instead. A family is a list of font to use in priority. So if the prefered font is not present, then you can advice on the next best choice.
Here is an html snippet showing how to use a font family:
<span style="font-family:Calibri, Verdana, Arial">Text</span>
You can apply this if you go to the source view of the template, in the template editor, and then manual change the font definition.