New to this software and testing it. Does anyone know how to find information about graphic file size rules? For example a banner logo that is on top of page for a letter.
File size is pretty much the same as for websites - as small as is possible, and probably smaller than you would use on the web.
With email there aren't really any rules about dimensional size - an email can be as long and as wide as you like. Generally 600px is the suggested max width for practical use though (email clients have narrower reading windows often) and keeping your headers short helps with small preview panes.