Personally I would just reply to the email --- they may come back and ask for more either way. If you wish to make a plea to the creditors then attach this as a letter which will be forwarded to them with the offer details.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk