The Word mail merge feature is a powerful and versatile tool that can be used for many purposes. If you need to send an e-mail message to a group of recipients and you do not want to disclose their e-mail addresses or their identities to the other recipients, you can use the Word mail merge feature to generate individual personalized e-mail messages with the same basic text that will be sent to each recipient with only one individual recipient's e-mail address on the To line. However, many spam filters treat such messages as spam and block them from reaching their destinations. Some users try to get around these problems by inserting the e-mail addresses of the intended recipients on the Bcc line. You also may not want your recipients to see their names somewhere down a long list.
You yourself may not always want your recipients to know your complete mailing list.
Some recipients may even feel that their privacy was invaded. However, sometimes some of the recipients do not want their e-mail address revealed to all the other recipients. In such cases it may even be useful for all the recipients to know who else received the message, and generally no harm is done. Sometimes all the recipients know one another or work together, and each recipient already knows or can easily obtain the e-mail addresses of all the other recipients. Everyone who uses e-mail has probably received an e-mail message with many recipients on the To line.