How to increase the size of the text in the viewing window

I just started using Apple mail that came with my new MacBook Air. The text is simply too small for incoming messages and also when I am composing messages. I have increased the preferred font size, but that has not changed what I see. Also, there doesn't appear to be a way to Zoom in to increase the size of the text - when I choose Zoom, it takes me to a full screen view, but the text is still too small. I never had this issue with Outlook and do not have this issue with Pages or other applications. Very frustrating!