With the Email Security.Cloud product the email disclaimers can be customized, but the input that can be entered is limited.
To customize the email disclaimers, in the Symantec cloud portal go to Services > Email Disclaimers and either select an existing disclaimer or create a new one. The default email disclaimer does not need to be active in order to create a custom disclaimer.
For custom disclaimers, only plain text can be used. HTML formatting cannot be used to modify the font, boldness, or to add images or logos.