Are you using the Outlook app? I have this issue using that app, but I also have the same email address added to Apple Mail and the Mail app pre-loaded onto my iPhone, and the email looks great on both of those apps, but not the Outlook app.
Wow, thanks, Ashley! I never thought that it was an app issue. I was using the Outlook app, and it looks great on the iPhone mail app. Thanks for your input - it makes me feel better to know that I didn't do something wrong!