Litmus is good for certain stuff and we use it a lot but we often want to send a test build of an email to a 'real' device in the studio so we can look at the code in-situ or get a more 'real-world' result (e.g. where we know exactly what browser or OS version it's being rendered on).
At the moment we use a feature we somehow discovered in Safari whereby we open the .html file and use command+I which opens the html page in Apple Mail, from where you can send it wherever you like. This seems to give realistic results but we can't really be certain that Safari/Apple Mail aren't adding their own stuff to the email's code. In any case, I don't imagine this is the preferred method used by bulk email companies ;+)
Does anyone have a good method for sending test emails which they believe is reliable and not prone to being splurged with proprietary/ extraneous gubbins..? How does everyone else do it?

Thanks in advance