OPINION: Do Not Mail Checks in Window Envelopes!

A couple of months ago, I wrote a check for about $200 to my pool company for the monthly maintenance. It was a computer-generated check that I mailed in a window envelope, which made it apparent that a check was enclosed. After about ten days, the check had still not cleared. I called the company and they said they had not received it. A couple of days later, the check cleared my bank twice, except the payee and the amount had been altered. Instead of being payable to my pool company for $200, the check was shown to be payable to a company and a person I had never heard of and were for a total of over $14,000.