Hi,
There are many ways to do this (depending on your budget) but the cheapest and easiest way that I can think to do this is to use a standard mail client (such as Outlook or Outlook Express) and create a group of contacts (as it is called in OLE) or a distribution list (as it is called in Outlook).
To do this in Outlook Express, follow these steps:
To create a group of contacts
In the Address Book, select the folder in which you want to create a group. Click New on the toolbar, and then click New Group. The Properties dialog box opens. In the Group Name box, type the name of the group. There are several ways to add people to the group: To add a person from your Address Book list, click Select Members, and then click a name from the Address Book list. To add a person directly to the group without adding the name to your Address Book, type the person's name and e-mail address in the lower half of the Properties dialog box, and then click Add. To add a person to both the group and your Address Book, click New Contact and fill in the appropriate information. To use a directory service, click Select Members, and then click Find. Select a directory service from the drop-down list at the end of the text box. After finding and selecting an address, it is automatically added to your Address Book.
Repeat for each addition until your group is defined.
For Outlook:
On the File menu, point to New, and then click Distribution List. In the Name box, type a name. Click Select Members.
In the Show names from the list, click the address book that contains the e-mail addresses you want in your distribution list. In the Type name or select from list box, type a name you want to include. In the list below, select the name, and then click Members. Do this for each person you want to add to the distribution list, and then click OK. If you want to add a longer description of the distribution list, click the Notes tab, and then type the text. The distribution list is saved in your Contacts folder by the name you give it.
When you have created your groups you will need to make use of the BCC (Blind Carbon Copy) field in Outlook / Outlook Express.
To open the BCC field on the View menu, select All Headers (for Outlook, choose BCC field).
Then just create a message with YOUR address in the "to" box and enter the distribution list / group name in the BCC box. This means that when the recipient gets the message, they will just see that it was sent to your address and no other addresses.
As I said, there are other ways to do it but this is probably the easiest and cheapest.
Hope this helps.
J.