The best way in my opinion to design an email template is to do the following.
Create your basic template that you would like the recipients to see and host it at www.thedomain.com/EMAILTEMPLATE
then in the template you just type the content to the email. you could obviously create a new folder for each email if need be.
Once you have then created this in the email its self insert the HTML and all of the image src should point to www.thedomain.com/EMAILTEMPLATE/IMAGES (example). On your email template at the top or bottom include a link saying:
" If you are having trouble viewing this email then click here" and then link this to: www.thedomain.com/EMAILTEMPLATE
Hopefully I haven't misunderstood you and I have been of help.
Bobski