Email is often the first communication you have with a prospective client, or an ongoing communication.  Considering email etiquette is therefore essential.  After all, how you deal with emails will say more about your company and it's values.

To get started, here are some tips:-

• Start your email with 'Dear Mr/Mrs/Miss' for initial contact.
• Once you are more familiar with the people you are communicating with, you can use "Hello 'name'" or even "Hi 'name'"
• Be prompt with your replies.  Your customers could well go elsewhere if you take too long!
• DONT USE TOO MANY CAPITALS!  This is generaly regarded as shouting and can come across as being rude.
• Spell check!  Bad spelling and grammar is shoddy and can come across very badly.  Always proof read before sending.
• Don't spam - we all get "funny" emails.. Do your clients have time to go through them all in their working day?  It can come across as you having nothing better to do with your time.
• Finish your email correctly.  If your email software allows you to add a standard footer, make sure it has your name, phone number and email address.
• Don't try to 'funk' up your email text with strange colours, large fonts or un-neccessary pictures.

If you have employees, I would recommend you have an email policy so that your customers get the same quality from each employee.

For more tips and further reading, take a look at the Business Email Etiquette Blog which has some good ideas on maximising emails for your company