We are using Google SMTP relay since past 3 years and had no issues. Since last two weeks though, we have more than 60-70% emails not getting delivered to the client. When we check the log it has TLS_Verified field value 'unverified' for some reason. We have already whitelisted all ips suggested by Salesforce in our Google app SMTP relay settings.
Google support says that we don't have whitelisted all the IPs that's why it gets rejected. In fact, Remote Host file in log is showing IPs that SF never asks to whitelist: 18.104.22.168, 22.214.171.124
Has anyone encountered this issue?