Hello,
in 4.1.0 I made some tests configuring the events' notifier service and I modified the file

/usr/share/ovirt-engine/services/ovirt-engine-notifier/ovirt-engine-notifier.conf

changing these:

# The SMTP mail server address. Required.
MAIL_SERVER=localhost
(I use postfix on engine server, configured with smart relay to my mail server)

# Specifies 'from' address on sent mail in RFC822 format, if supported by mail server.
MAIL_FROM=ovmgr1@mydomain.it
 
# Specifies 'reply-to' address on sent mail in RFC822 format.
MAIL_REPLY_TO=some_group@mydomain.it
(it seems it is not honored.... in the received e-mail if I click reply I get an empty To: field...

During update to 4.1.1 the engine-setup failed in closing phase, due to the file being overwritten by the 4.1.1 package version of the conf file.

[ INFO  ] Stage: Closing up
[ ERROR ] Failed to execute stage 'Closing up': Failed to start service 'ovirt-engine-notifier'

I fixed it creating a file 20-mailsetup.conf under
/etc/ovirt-engine/notifier/notifier.conf.d/

Is it the correct location? 

It was not so clear reading this page when configuring it....
http://www.ovirt.org/documentation/admin-guide/chap-Event_Notifications/

Thanks,
Gianluca