This was a few (3) years past, but they accepted root@localhost sendmail messages just fine in most cases, and delivered alerts within a minute or two of sending. We didn't rely on this long term, but it was a "good enough" first pass.
I'd probably recommend using one of the gateways (or a more fully-featured service like Pagerduty) for more serious businesses, but for personal use (or where an outage detected the next day isn't crippling), it's remarkably useful.
I'd probably recommend using one of the gateways (or a more fully-featured service like Pagerduty) for more serious businesses, but for personal use (or where an outage detected the next day isn't crippling), it's remarkably useful.