Troubleshoot email on a new Discourse install

[Architect]

@Bryan_Bai

Validate your sender or authenticate your domain

For sender address can be set to mail subdomain you are using to send mail, such as mail@domain_address.

To authenticate subdomain + sender there are a few steps for that they have a guide here:

Prepare for Gmail and Yahoo's new requirements for email senders

Authenticate your domain with Brevo (Brevo code, DKIM record, DMARC record)

Create a new sender