Yes this is possible through the Group in Yahoo .
Put all the email of your customers in the Yahoo Group and when your customer join the group you could able to send a single e mail to all group members .
This is one of the easiest and cheapest method .
Thanks
S K Somani
QuickBooks can’t do this on its’ own. However, there is an add-on QB’s product called Customer Manager that can. It can synchronize contact information with QuickBooks and/or Outlook. You can categorize the contacts into groups and send emails to everyone at once.
Learn more here…