72 Definitive Reasons Why Your Emails are Going to SPAM (Reason 27 Will Blow Your Mind)
SendX
JANUARY 22, 2019
Multi-part MIME (Multipurpose Internet Mail Extensions) bundle together a plain text version of your email along with the HTML version. Check out this paper from Microsoft Research that talks in depth about this topic. You will find very similar patterns in phishing emails as well. didn't come up with this theory.
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