to give you an example of the font size i like to have in conversations and the email client.

this forum in classic style i can see in a none full screenmode 8 topics at the same time and those 8 topics have then a subject line and a line below what could be used in modest as the first line of the email. besides that i also have plenty space on the right for sender info and so on.

so the browser shows me in a default zoom perfect info in exactly the size i want. would love to have that in the other places