Hi LaG,
If this happening on a standard screen? If so what screen is it? If you edit that screen what is action 48?(based on the error I think its the Send Email action). Are you able to send any other emails through Method?
-Michael
Michael Melo
Product Manager
Method Integration Inc.
Website: http://www.method.me
LinkedIn: http://www.linkedin.com/in/MichaelMelo