You should be able to fix the readability of this without hiring a designer. Not that you shouldn't hire a designer, but you shouldn't wait to fix it before you hire one either. Since email is all about text, if it looks unreadable that's going to be a big turn-off. Read at least the next paragraph of my post!
To start, I would reduce the font sizes on your header-type items somewhat. It's clear that you're using large fonts and bold to emphasize key information (which is the right idea), but a heuristic I've found is that if you're using bold, your font doesn't need to be as big, or if you're using a large size, you may not need to be bold. When you do both, it's like an assault on the eyes, which you don't need here. Doing this alone would make your app like 75% better (note: I made that number up entirely and don't know very much about your app.)
Next, you could tone down the reds (I would change the hard red #F00 color to the softer pink-ish color, and then reduce the pinkish color further), and exchange the black on white for something else. For your icons, you could experiment with grays (I like to start with #333 and then go up or down), so they're less overwhelming.
Finally, add some labels for your icons. Remember how you made your fonts smaller before? Well that applies to these labels. They should be contrasty so you can read them, but otherwise it's fine if they're subtle.
A couple of minor points about your website: the proper name of your competitor is Gmail, not GMail. You should add more spacing between your icons and the text (it feels crowded currently.) Also, your circle arrow jobs are getting cut off at the bottom.
Finally part ii: don't forget to steal from others. Obviously I don't mean blatantly stealing a design, but just check out what other sites do. To do this effectively, you have to pick a particular thing and examine it closely. So for example, if you want to figure out how to do headers, go to other sites and see what they do to give emphasis to things without being overwhelming.