When you open

<https://impulse.news-mailer.com/u/archive/8yfFA1RRSMbdQR7YfftNbQ>

an make a right-click on any picture in it like

<https://images.maileon-static.com/c/zal814kuI_dHJO3DR6z99A>
<https://images.maileon-static.com/c/AWn6DIky2iOupCfTd27jvA>
etc.

these are the files that are not saved.