When you read a message stored in your Mailbox, you can click the Reply or Reply to All link/button. The Compose page appears and allows you to enter the text of your reply message.
If you click the Reply link/button, the original message Reply-To header field is automatically placed into the To field of your reply. If the original message did not have the Reply-To header, the original message From field is used.
If you click the Reply All link/button, the original message Reply-To/From address is copied to the To field of the reply message. Then all addresses from the original message To fields are added to the reply To field, and all addresses from the original message Cc fields are copied to the reply Cc field.
The text of the original message is formatted as a quotation and copied into the message body text area. The following Settings control the formatting process:
Note: if the Reply Header field is an empty string, the original message text is not automatically added to the reply text.