AuthSMTP is a nice idea and I would pay their rates if they were metered like Amazon's Web Services. The problem is that I often don't know how many emails I'l

AuthSMTP is a nice idea and I would pay their rates if they were metered like Amazon's Web Services. The problem is that I often don't know how many emails I'll need to be sending. For example, let's say they had a simple charge of $0.001 (one tenth of a cent) for each email sent plus $0.005 (one half of one cent) per MB sent. That would work nicely (and be in line with what they currently charge). The problem is that I have to decide on what plan to buy. AWS' model works nicely in that it works for a tiny bit or a lot.