Does Microsoft Exchange automatically rewrite incoming HTML e-mails as multipart/alternative?

Question

Given:

• If you're sending an HTML e-mail, and you'd like to avoid spam filters, it's advisable to compose your e-mail as a multi-part message and include a plain text version.

My Question:

Does Microsoft Exchange automatically rewrite incoming HTML e-mails as multipart/alternative as a benefit for the user?

Answer 1

It does not. Doing so would break S/MIME compatibility.

As proof to the pudding, I'm looking at an email from Microsoft itself (support case) and it doesn't have multipart/alternative. Neither side (we're Exchange 2007, they're something very beta but still Exchange) put one in.