Ask HN: HTML styled newsletters? or Plaintext?
Which do you prefer? or don't care?
Based on personal experience I believe those who don't live and breathe this stuff 24/7 prefer a little window dressing.
If it is styled, I recommend minimizing the amount of scrolling required to reach your text. (For example, I don't see much value in a large header mit logo.)
But test, and ask the same question of your prospective readers, if possible.