There is the ability to change font type, size and color but it only seems to effect messages you draft, I don't see anyway to change the font of received messages.
If the Win 8 mail app doesn't work the way you want, why don't you install a different mail client? Personally, I use Windows Live Mail but the are others such as Thunderbird. This may not be an option for you if you are running an RT version of Windows 8 since you are limited to whatever mail clients are available in the Windows store.
500GB ssd boot drive with 2 & 10TB Data on Desktop, 512GB ssd for laptop, 128GB SSD tablet, 500GB ssd laptop
Corsair CX 750M
Coolermaster CM 212+
IBM Model M - used continuously since 1986
MSE on desktop, Defender on laptop
Retired after working in the tech industry for 41 years. First 10 years as a Technician, the rest as a programmer/software engineer. After 1 year of retirement, I was bored so went back to work as a Robotic Process Automation Consultant.