When sending out an e-mail, try to keep your communication between 20 and 60K in file size. Also remember many people do not scroll. Put your best offers “above the fold”. For long e-mails, consider inserting a hyperlinked Table of Contents or Index at the top so recipients can quickly click and jump to where they want to go. Also try to keep the width of your newsletter to 500-600 pixels. Any bigger and you may cut off relevant information.
eINFO – a collection of articles and studies about email marketing.