Plaintext vs HTML email is an interesting one - I found that getting deliverability to MS 365 from a very low volume, self-hosted email server was actually impr

Plaintext vs HTML email is an interesting one - I found that getting deliverability to MS 365 from a very low volume, self-hosted email server was actually improved by sending in HTML format, as opposed to plaintext. This was the exact opposite of what I expected, but every other reasonable variable was controlled as much as possible.