Unfortunately not in headers, only in the body (as noted previously in this discussion).  The headers use fixed fonts hardcoded in the program.  Fixed fonts are also used in a number of other places (configuration windows come immediately to mind). 

Workarounds to the small fixed font size on hi-res monitors are to increase screen resolution or use a magnifier app.

Strange and maybe little off the wall compared to others with more major problems

but probably easy to solve... I must have done/selected something to change  my fonts.

Color is okay in message header but not BOLD as before same as in reply message listing

 quick fix?

Thanks in advance

The font on both the header and body of the reader window can be set by using either the font button on the main toolbar or the Reader > Font pull down menu option.  This must be done when a reader window is active.

Same goes for the font in the body of a reply except the pull down menu option is Message instead of Reader.  The font of all of the other text in the reply window is hard coded.

Thanks for replying Brian but I see nothing that will bring bold into both header and message.

Tried looking at font window but nothing

The font selector window allows you to set the font face, size, bold, & italic. 

The setting will apply to both the header and the body of a reader window but only to the body of a new message window.

Any way to change the default font size when composing a new email?