I started building a SaaS for the legal industry around 2004. It was very small targeted at specific industry. Back then it was very hard to get everyone on board to use Credit Card. I ended up automating everything (including the monthly billing sent directly the user's inbox), but because of difficulty of payment gateway processing (getting a merchant account, parsing the authorize gateway code)

And since I was a one man shop, I just had my users to send me checks at end of the month. I was not the best organized person back then. So let's just say there were quite few uncashed checks. Really wish Stripe was around them.