Make sure SSL is checked and make sure the smtp port is correct. Also, I aways use Gmail for email notification since some others do not allow emails thru the dvr.
Its the same gmail that works...on new dvrs and I checked the ssl box.on machine. The dns settings keep unchecking also.on static.or dhcp ip . Im at a loss
Has the customer changed his ISP? Sometimes they put a block on certain type of emails going out. Are you using a gmail account and sending to a gmail account? When you click test, do you get fail?