Please make the paper clips image brighter on the dark background (in dark mode).
Make the attachment icon brighter in dark mode.
Riaan van Dyk commented
Yes, please! I have to use a pair of opera binoculars to see which emails have an attachment!
Dark theme - The attachment icon / symbol in the message pane (not to be confused with the preview pane) is too dark and is hard to see.
Instead of using a dark grey shade for an attachment symbol, could this be made white like the subject text itself to enable a better contrast against the dark background.
Apart from that I do like new office and new icons overall..