Getting a lot of users' contact me with bounce messages. Is this a result of mail sending policy change?
Can you paste a copy of the bounce for me to look at so I can see what the cause of the bounce is?
Email is not being sent to certain people with the error message as follows. Please advise. In this case it was an email to a Gmail account, but it has happened to other domains.
550-5.7.1 This message does not have authentication information or
fails to pass 550-5.7.1 authentication checks. To best protect our users
from spam, the 550-5.7.1 message has been blocked. Please visit 550-5.7.1
https://support.google.com/mail/answer/81126#authentication for more 550
This could be because of DKIM and SPF not being setup I believe?
That is exactly the reason why. Google is starting to require it when sending to them. They did this about 5 months ago but really started enforcing this in the past few weeks.
You can see the guide here for enabling DKIM and SPF.