Well, if you can't drag the water to the sea, drag the sea to the water
You may (or may not) be aware of API interfaces on Dahua (and probably Hikvision):
GetActiveUserInfoAll
URL Syntax http://<ip>/cgi-bin/userManager.cgi?action=getActiveUserInfoAll
Comment Get active users.
Response users[0].name=admin
users[0].ip=10.43.2.16
users[0].group=admin
users[0].clienttype=web3.0
users[0].logintime=2011-11-08 09:51:03
You can "query" your device every 1s and work around that information for sms/mail information.
Good luck!
CC