If you know how to use scripting languages you can change the appearance of the Postcard portlet.
Use custom template for appearance
Changing this template will alter the appearance of the form (Title, Message, To, E-mail, Your name, Your e-mail)
Use custom template for preview
Changing this template will alter the appearance of the preview for the postcard but not the actual postcard.
Use custom template for postcards
Changing this template alters the appearance of the postcard and the greeting that is sent.
Use alias in postcard URL (alias must exist for this page)
Normally the whole address and an id-number is sent for the postcard. If you instead want it to send http:// <server>/postcard you can check this box and type the same name that is stated beneath the properties for the web site, Website settings->Alias. That is an, an alias already need to exist for the page.
Limit number of days the postcard is available
Here you indicate how many days a postcard should be stored on the server. The postcard is removed after selected number of days. The removal of old postcards is done every night, e.g. when the best before date have passed.