To forward a message to someone whose email provider can read only plain text, you can use Internet-Style Forward.
Select the email and then click Forward > Internet-Style Forward
above the message list.
This option sends the message in plain text, so Internet mail providers (which sometimes can only read plain text) can still display the information.
This style of forwarding includes no pictures, attachments, OLE objects, or collapsible sections.
You can also change the line length or the character that begins each line in Internet-Style Forwarding