Troubleshooting Print to Email
some reference material here https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/fix-issues-with-printers-scanners-and-lob-applications-that-send-email-using-off
If you are printing to email via a google account remember to turn on “Allow less secure apps” on the account or you won’t be able to print to email. the error messages are spectacularly unhelpful.
Sign into the google.com web account that you want to use to scan to email or send alerts
click the 9 dots in the top right
click account
click security
scroll down to Less secure app access and turn it on

I have noticed this get turned off (by google?) very infrequently