Thank you for the reply.
The article you reference is for a later version of web service than the 2012 version on my dvr, hence some differences:
The email settings to not include an option for setting SSL encryption.
There is no box to check for sending an attachment on the Network/Email config page.
The 'user name' and 'password' was previously for the dvr. I tried using my gmail address and password but the 'test' still failed.
As for email settings on gmail, the dvr emails previously went through fine. I have long had a separate mail box for them. I looked through the many gmail settings and don't see anything which would block the dvr and they haven't been sent to spam.
I think that covers points made in the referenced article.
The only change since the emails stopped working was a change of the modem. It seems to me that there should be some place in the web browser to direct the email through the new router. I did put the new modem/router address for both local wifi and external viewing into TechproSS and can view the dvr output either way. The web browser also picks up the dvr through wifi and hardwire.
The email 'test' button continues to fail.
Again, the emails the dvr sent previous to the modem/router change show the 'Sender IP' as the previous router's address. Where do I enter the new router address for email?