Here's a method to overcome garbled text in received email messages.
Email is a very mature technology relied on by consumer and business users alike. Because email is based upon a set of well defined, open standards and protocols most email messages can be sent and received from any system to another without concern for what operating system or email client software is used.
Sometimes however message text can be poorly formatted and difficult to read. This is known as "garbled text" and can be caused by the encoding used by the sender’s email system.
One workaround is to use the Message text garbled option within Gmail.
When viewing a message click the down arrow next to Reply at the top-right of the message pane and select Message text garbled. This will open a new browser tab showing the raw message text, including header information with no markup or layout.
This is a tip you won't need to use very often but it can save the day when some vital information is trapped in a badly formatted message.
If you need more information about why messages aren't displaying properly, check out this Gmail support page.