How do I send a campaign to myself first to check it?

Test mode redirects every campaign to your own inbox instead of your customers, with the real recipient shown in the subject line, so you can read the real thing before anyone else does. It lasts seven days from when you turn it on. After that, campaigns go to your customers again even if the switch has not been turned off, so check it before a send and turn it off yourself when you are done testing.