In my raw installation I need to define the from address in checkmk for every notification rule, and global settings (fallback mail) to be able to send mail.
Do you have that set as well?
(copy paste my comment from earlier post last week) 
In my raw installation I need to define the from address in checkmk for every notification rule, and global settings (fallback mail) to be able to send mail.
Do you have that set as well?
(copy paste my comment from earlier post last week)