My guess here is that the sender is not sending it from MRSware and you are not viewing it in MRSware, whatever device is sending it is sending it in a format that the device you are viewing it on cannot understand. Last time I saw this it was some combination of Blackberry and iPhone mailing back and forth to each other.
There is not anything really you can do about this directly on your device. You can view the email in MRSware, where it should appear fine. Typically we recommend that people send out the majority of their messages in plain text format, since this is the most standard format that should work no matter what the device the email is being viewed on; however, it is up to the sender to set that preference, so once again something that you can't effect directly.
You can set the default format in MRSware to text, which at least would start any conversation off in the simplest formatter form: