On 02/13/2016 08:19 AM, Shea Alterio wrote to mailman-users:

Thanks a bunch for your response, it was very helpful.

...

‎Are you sure your script is generating the multipart/alternative mail correctly? What happens if you sen such a message from your MUA as opposed to your script? Is the problem with all such mail or just mail generated by your script?

If I send it from a MUA, the text/plain+text/html is delivered without issue if sent directly to other accounts. It is properly formatted and looks as it should. If I send it into Mailman I get just a text/html+text/plain email, but all the html etc. Is shown as raw code, as if you were to paste html code into a word processor.

I'm copying this to mailman-developers@python.org and requesting replies to go there.

What you see should obviously not be happening, but a cursory inspection of the doc tests which the code passes seems to show this situation is covered.

In the message received from Mailman, do you also see MIME headers and boundaries (i.e. headers such as Content-Type:) preceding the text/plain and text/html content, or do you just see the plain and html text?

Also, what is the python3 version that Mailman is using?

For further analysis of this can you create a very simple test message in an MUA and send it to a list? The body can be a simple line or two. Than can you post the entire, raw message source of the sent message and of the message as received back from the list.

-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan