You can set up Web Messaging so that when you forward a message, you can also edit the message; if you do this, the forwarded message is flagged as an "Original Message" and shows the From and Date fields.
From the Account Options... menu, select Set My Preferences.
On the User Preferences page, locate Forward Editing and select Edit original message.
Click the Save Changes button at the bottom of the page.
You can also set up Web Messaging so that when you forward a message, the person to whom you forward the message sees the unedited body of the original message displayed beneath any text you enter. However, you (the forwarder) will not be able to view the body of the original message as you add your own comments.
From the Account Options... menu, select Set My Preferences under My Options.
On the User Preferences page, locate Forward Editing and select Don't edit original message.
Click the Save Changes button at the bottom of the page.
Note that this setting stays in effect until you reset it; therefore, if you want to edit just one forwarded message, you will need to:
Set this preference to Edit original message
Forward the message
Re-set this preference to Don't edit original message