An email address book, which is a collection of all your contact email addresses and other information is one of the most useful feature in email. The advantage of creating this email address book (or also known as mailing list) is that you can send message to many people without having to type the email addresses one by one in the destination fields provided. You can simply open the address book and check the boxes next to their names or next to the names of lists. When you are done selecting recipients, click the "Insert Checked Contacts" (Yahoo) or "Email" (Gmail) then all of your recipients’ email addresses should appear in the “To”, “Cc” or “Bcc” fields and the email you send will automatically go to all of those contacts (easy enough right?).
You can also group email addresses in your address book into various categories, for example; category of school friends; in this category contains all the email addresses of your school friends, category of coworkers; in this category contains all the email addresses of your colleagues or your coworkers, family category; contains email addresses of your family members or relatives (click here to find out how to create a category in the email).
Open your Yahoo email, on the first page on top left side click Contacts tab, once clicked the Yahoo address book page will appear, then click Add Contact, after that you can fill in the email address and other information you need to put. You need not fill in all the fields, only the most important parts will be enough such as the name, nickname and email address. When you are done click Save and after that you will be able to send message to many people in an address book with so much easier (click here to learn more about how to send an email to several people at once).
As for Gmail, click Contacts on the left of the page and then click add button (“New contact” button) at the top left corner. After that your contact data input form will appear, fill out the form (You do not need to fill in completely, just the important ones such as name and email address). When you are done click Save and now you can send one email to many people in an address book (click here to learn more about how to send an email to several people at once).