When I say I'm using PERL, what I'm actually doing is using a PERL program to generate a text file, which I then pipe into sendmail.
If I examine the text file, both the html and the text alternatives are headed by:
Content-Type: text/html (or text/plain);
After I've received the mail from the mobileme server, the plain text part is exactly as I sent it, but in the html part it's been altered to:
Content-type: text/html; CHARSET=US-ASCII
I don't see how or why this should have been changed. And why just in the html section?
I'll try changing to base64 to see if it makes any difference.