This perhaps doesn't answer your question, though it may solve your problem. Feel free to delete.
I had a similar situation and ended up using something like this very simple macro below. I tested it a few times, played around with the delays and then put in on repeat for the next 40 times, with a few more delays.
If I did it again, I would use variables rather than clipboards. It can also be done with applescript, but for quick and easy, this is the way I did it. Also, I was using airmail, so you'd need to change those setting to make it work in mail or whatever you use. It ain't pretty but.... 
There are certainly 'better' ways to do it.
Of course, since you are comfortable extracting the values from the excel file with python, there are plenty of example applescripts demonstrating how to the create an email. See here: http://preserve.mactech.com/articles/mactech/Vol.21/21.09/ScriptingMail/index.html
here: Scripting Apple Mail
and this thread seems to be doing a very similar thing: pulling-in-variables-from-a-csv-file-to-use-in-mail-merges
Repeat.kmactions (8.8 KB)
