It is essential for any standard EDM to have a header image that is event-oriented and would match the overall EDM layout. For consistency of design, the header image is used on the Invite, Confirm, Details, Surveys, Registrations and PDF copies.
A designed header/hero image (min 600px wide, this can be a gif as well) OR a logo (min. 100px wide, can be an image - but best supplied as jpeg or png)
Hex-codes for the highlight colours (RSVP call-to-action button and table background colour) or theme.
For the RSVP Landing page design: A logo file Hex-codes for the button colour, and the background colour is required.