If you want to discuss two different issues it might be better to send two emails, especially if the email is being sent to a lot of people. That way you can also send only the information necessary to each group of people. Watch your attachment size . Some people are still on dialup connections, and getting a one megabyte attachment can be very annoying. For very large attachment you might use a service like Xdrive or Freedrive to store the attachment and include a link in your email.
Signatures are cool .
Four to seven lines is fine. Use the importance flag . This is an excellent way to send to lots of people without giving out all of your friends email addresses to everyone on the planet. ALL option . I've found that sometimes, especially in the corporate world, people send emails to way too make people.