@emotion said in Email suddenly no longer works with SMTP Relay Google Workspace:

The problem with letting postfix relay the mail is that it lacks DKIM, DMARC, and SPF records which makes your emails more likely to end up in the spam folder.

I'm using postfix to relay all mail to gmail. It ends up being the same thing as if you set the relay in NodeBB.

@emotion said in Email suddenly no longer works with SMTP Relay Google Workspace:

How are you connecting WordPress to smtp-relay.gmail.com? Are you using a plugin?

Yes, I use WP Mail SMTP

I am using the gmail smtp relay

I had the same thing happen. Emails have been working fine when using the gmail smtp server for months. Then a few days ago it stopped working with the same error as mentioned above. I have a wordpress site on the same server as nodebb with the same relay settings and it continues to work fine. It also works fine when using telnet from that same server. NodeBB is the only thing that seems to be effected. I solved the problem by disabling "Use an external email server to send emails" and just letting postfix relay the mail for me. Just thought I'd share.