I've looked all over and can't find a solution or how to approach this.
We have 5 Revive installations since 2013. Our installations are up to date. Sometime around May this year, email notifications to advertisers and admins (campaign ending) stopped being received. Our server is set up the same as our others and we can successfully send mail via the command line. We can also send mail using php. It seems to be an issue with revive itself sending mail. We'd like to debug that, but we're not very familiar with the code and what needs to be fixed.
In looking at the logs, it appears that Gmail may have changed something in their security settings and that the emails are now failing to send (by Google). Something to do with the email sender configuration - which hasn't changed on our side over the years.
Have you heard this before? Any suggestions? Thank you.