I like to share with you my cents on using fonts.
Writing spec and emails,
- Most people use Arial
- Verdana is also often used
- Somebody uses Comic Sans MS, including Kevin Johnson.
If the document is for formal print, Times New Roman and MS Sens Serif are also the best choice besides Arial. Though they may be not comfortable to read on the monitor. Verdana also looks great on monitor as well as on paper.
Hope this could help us write more decent emails/specs.