To change your signature details select the tab and then the Signature link under the Additional Options title.

Check the box at the top of this page to append a signature to all the emails that you write, reply to, or forward. Enter the text that you want to appear in the box beneath the checkbox.

When you click the button on the Inbox page Web Mail will place the signature into the message in the Compose Message Window. When replying to, or forwarding mail, the signature is at the start of the message. See Compose Message Window for details on sending a message.