Do you mean to show them below the FROM?

generally the CC CCO fields, etc. are shown below the from

So the same column, not the same line :)

We need to improve the display of headers. Any suggestion? Share your mockups/screenshots :)

I'm sure that users will appreciate some more traditional design ;-)
For inspiration - here are some nice skins from demo.roundcubeplus.com

droid.png (204,116 bytes)   

droid.png (204,116 bytes)   

droid+.png (234,941 bytes)   

droid+.png (234,941 bytes)   

droid+2.png (252,384 bytes)   

droid+2.png (252,384 bytes)   

gmail+2.png (241,961 bytes)   

gmail+2.png (241,961 bytes)   

icloud.png (127,673 bytes)   

icloud.png (127,673 bytes)   

outlook.png (155,230 bytes)   

outlook.png (155,230 bytes)   

My 2ct:

• email addresses should always be shown, not just the display name
• Header should be more distinguishable from Body
• Subject and From should be equally important, therefore in same size and font and bold.
• S/MIME signatures and encryption icons should be shown right beside the Subject

Just remember that we need to stick the Google's Material Design (https://material.io/) and keep all interfaces responsive.