Create a Group Email List in Yahoo Mail
To set up a list for group mailing in Yahoo Mail:
Select Contacts in the upper-right corner of the Yahoo Mail navigation bar. Select Lists. Select Create list in the pane below Lists. Type the desired List name for the list. Add at least one contact in the Add contacts field, and then select Save.
How to Add Members to a Yahoo Mail Group
To add members to the email list you created:
Select Edit next to the list you created. Add contacts in the Add contacts field by entering their name or email address. Select the name that appears to add that address. Repeat this process until you have all the email addresses you need. Select Save to save your new list.
How to Send Mail to Your Yahoo Mail List
You can now send messages to your Yahoo Mail mailing list:
Select Compose in the upper-left corner of the Yahoo Mail web page. In the To (or CC/BCC fields, if used), enter the name of your newly created mailing list. It should appear when you start typing. Select it when it does. Continue composing your message and send it.