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.
Verdana, Arial and Comic Sans MS are most accepted fonts for emails/specs because they are comfortable to read on the monitor. For most time, avoid using other fonts: Courier New is for code, Tahoma, Georgia, Franklin Gothic and Bookman Old Style are not formal for business use.
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.