YOU as a company have partnerships with vendors. This is complete horseshit of an industry answer. If you check out this article or you can see some very useful alternatives and advice on using Dropbox, IFTTT and ISP email servers as a better option for alerting such as push notifications and access to snapshots and some video as well. As noted by Robert Thomas in his post, it is possible to use your internet provider's SMTP server address and send emails that way (ISP type emails should work, Google and Yahoo both also block these emails now though) but if you send too many they may also classify it as SPAM and stop you from sending. To resume the service we have to reduce the incidence of this SPAM type sending to an acceptable level.
The result of the large volume of emails from poorly set systems resulted in our service provider sending around 130 million emails a month with some users sending the same alerts to 3 different email addresses and using settings that caused almost constant triggers.
The auto email system that is the default in our later model DVRs and NVRs has been suspended by our service provider due to SPAM abuse, where a small number of our users are sending thousands of emails every day which is not in scope for our service.