Adding custom options for a message in Webmail, is a good way to personalize your message.
To add custom options for message (rich text):
Select a message, (this could be a message you have received, or you could create a new message by pressing the New Mail icon in your inbox toolbar.)
If this is a message you received, click on the Reply or Forward option in your toolbar.
Once the message is open, click on Options.
Place a check mark under Rich text.