Do you want to know how your email look like in different email clients? It is a smart move to check how (for example) your newsletter will be displayed on different devices using different email clients. To avoid any problems with design, preview your email with one of the tools available on the internet.
I use and recomend Litmus that claims to answer an important question - "Does your email look beautiful everywhere? ". It is simple to use, FREE and it enables you to test your email across more than 30 email clients.
To start previewing your campaign visit Litmus site.