Domain Email Account.

To keep your emails and business more organised and seperate and to look more professional, its better to use an email address such as  [email protected] however more and more people are using there domains in there gmail accounts such as  [email protected]

Neither of those emails exist, they are just examples.  Some hosting companies like godaddy, will charge you a monthly fee for a seperate email account per domain, some hosts like 1&1 let you set them up for free. 

I prefer to use Googles email solution for businesses, its difficult to set up for an amature, but there are good instructions to follow, it works by messing with your DNS / MX records. It costs 50 USD per year, but its worth it.

http://www.google.com/apps/intl/en/business/index.html

To manage several email accounts, I recommend the free software from the makers of firefox.  Thunderbird.