The best thing you can do is post a link to view the source of your email to see what is going on for us to offer specific support. In cases like these its best to make sure you are defining your fonts in em/rem which base sizes based on settings in the browser/app for the user.
The best thing you can do is post a link to view the source of your email to see what is going on for us to offer specific support. In cases like these its best to make sure you are defining your fonts in em/rem which base sizes based on settings in the browser/app for the user.