One issue all small businesses face is getting the word out to customers, but in a way that is effective and not instrusive. If you are still managing mail lists by hand, its worth taking some time to consider the advantages of paying for a service to manage your contact lists for you. Two that are popular are MailChimp and Constant Contact. Both can integrate easily with a drupal website. The key advantages of a third party mail service are:
1) Your customers can add and remove themselves from your mail list. Its easy to understand why you would want to let them ADD themselves, but you need to allow them to UNSUBSCRIBE easily too. One of the biggest reasons businesses get tagged as a "spammer" is that you repeatedly send unwanted mail to a mail address, and that person reports you. If enough complaints are filed against you, then anti-spam software used throughout the internet can and will start blocking anything sent by you.
2) Deliverability. Mail sent from MailChimp or Constant Contact is FAR less likely to be deemed spam because both of these services monitor how their service is being used, and also provide useful tools to help you deliver content that won't be considered spam. Much more of your mail sent through a service like this will get through to your customers.
3) These services offer tools to help integrate your mail blasts with your social network presence (like automatically posting to FaceBook, or making it easy for people to "like" you directly from your email, or follow you on twitter, etc.)
4) You can save your past mail campaigns and create templates that help you design new messages and save time.
5) You can monitor statistics about the effectiveness of your mail blasts including open rates, and if they clicked on links contained in the mail. This will help you determine if your message is getting through.
6) You no longer have to clean up email addresses that are no longer valid. These services will remove email addresses that do not work anymore.
Here are a couple of great articles to check out:
Comparing MailChimp to Constant Contact: http://www.cloutsmiths.com/2011/mail-chimp-vs-constant-contact/
Why you should use a service: http://www.cloutsmiths.com/2011/five-reasons-to-use-a-3rd-party-email-marketing-service/
Learn about MailChimp at www.mailchimp.com
Constant Contact: www.ConstantContact.com