$1.50/1000 seems steep and could hurt should a spam attack occur...Someone needs to package charged outgoing, with free incoming. Kinda like the cell messaging systems they have in the UK...
Remember, you can add value by combining valuable services. Sell one as a loss leader to bring in the users and the other is your revenue stream.
You could always use Postmarks spam checker service to monitor emails and if you get say 2 or 3 from the same email address that flag up as spam block the email?
Assuming I could craft messages which did not look like spam (to your system), and I could do it really really fast, do you have any throttling options to allow your customer to prevent an excess of mail from adding up too quickly or an alert based on a threshold? (Maybe i'm overthinking it, but I like services that put me in control of how much money i'm spending instead of being at the mercy of botnets)
"Unusual" send activity is pretty easy to spot, especially if it's going to put our customer at risk in any way. We're extremely proactive about making sure that you're aware of anything that might be considered a "surprise" to your service or your wallet.
My first thought: How would this service handle 100k forged emails sent from china? The recurring payments is okay if you set maybe a daily max, example: charge me indefinitely but no more than a dollar a day. If my daily quota is hit then cut that email address off until the next day.
Do they (or a similar provider) already offer a better solution? I didn't find anything in their docs but I might have overlooked it.
We use a combination of algorithms and humans to determine "unusual" activity (not just spam or forged emails) and act accordingly.
We're even proactive about finding customers who break into new send volume thresholds and offer them discounts. We'd much rather have high quality senders in our network for a LONG time than just keep the highest billing rate on autopilot.
Remember, you can add value by combining valuable services. Sell one as a loss leader to bring in the users and the other is your revenue stream.