Sharepoint - Why are outgoing e-mail alerts not sending?
It's solved for now. "stsadm.exe -o setproperty -url https://our-portal -pn alerts-enabled -pv true" command typed many times WITHOUT manually started imm. alert jobs works. Maybe it is my fault, when no alerts come in 5 minutes, I opened CA, start job manually, do some changes and type command again. If I leave it alone at the end, it works. Or maybe it is a coincidence and farm was confused by DNS changes.
I finally fix this after following steps
in my case initial confirmation emails was sending but future change alerts were not
allowing all sharepoint servers in the farm to relay email in Exchange server fix the problem
you can also change the prefered Server for Timer service for each Content database in central admin (/_admin/CNTDBADM.aspx)
also note that the server which Immediate and Daily alerts are sending from, are shown in central admin. play with services and you will find it is running on your one of your servers (/_admin/ScheduledTimerJobs.aspx) .
http://sharepointalert.info/2009/11/troubleshooting-sharepoint-email-alerts-check-email-setupinfrastructure/
http://sharepointalert.info/troubleshooting-sharepoint-alerts/