Help! Sent a signed lease to a prospective out of state tenant... she hasn't returned it! Now what?

[Wendy Brown]

Out of state couple contact me. Corporate transfer to my state. They see the house on CL. Send their best friends in the whole world to check it out. Friends love it. The prospective tenants say they want it. I email an application and tell them we want $3750. for first months rent and security deposit. She says "no problem" They emai back the application. I email them a lease She looks at it. Says it looks fine. My husband emailed them a signed lease and asked them to sign and send back with a check for $3750. It has been 5 days and I haven't heard a word. Left a voicemail message this morning asking them to let us know if/when they will be mailing the lease/check. If we don't hear anything can we send them an email and cancel the lease? They aren't supposed to move in until April 1.