hmm... do you have rich text selected in mail>preferences>composing? or plain text, don't know if that would make a difference, but worth a try.
also, how are you pasting in the body of the email? as an image or directly from pages to the email, are you using the straight paste, or are you using paste and match style from the edit menu?
finally, a word of advice, although stationery works with most recipients, it does not for all, and especially for outlook users because of a MS issue not recognized the format in which an email with stationery is sent. you may want to search these pages to find out what other users have found when sending stationery.
hope this helps