Hey guys, newbie here, need some help, I need to make a device that conected to some sensors automaticaly notifies by mail every time each sensor changes it´s status. I´m flexible on router model. If it´s been done and anyone want´s to share I will apreciate it. Any other input that shorten my research time and learning curve will be very apreciated too. TIA

I use ssmtp (opkg update; opkg install ssmtp).  You need to modify ssmtp.conf to set appropriate values, for example, "mailhub=smtp.comcast.net", "hostname=someplace.com",
  "root=youremail@yourprovider.com", "FromLineOverride=YES"

Then you build your message in a file and send it:
ssmtp youremail@yourprovider.com < /home/mydir/mymsg.msg

There are many other ways to do this.