Mail App tiny fonts incoming messages

Hi,

I've been trying to use mail app on High Sierra for a couple of weeks but because some emails received are rendered with such a tiny fonts, it's not usable.

It seems to be email received from Outlook senders and IBM Notes that the fonts are really tiny.

Following command seems to work on some emails when set at 16 or over. Under 16 it does not make changes:

defaults write com.apple.mail NSFontSize 16

I cannot believe that the only way to be able to read all emails it to use cmd+ on every email in order to read them...

Any ideas or suggestions?

Thanks