Does Discourse officially support domain webmail SMTP for activation emails, or is Gmail / third-party SMTP the expected setup

[itsbhanusharma (Bhanu Sharma)]

@simon_tong

is it recommended to use a domain webmail address (e.g. admin@mydomain.com via local/Postfix/webmail), or should we always use external providers like Gmail for reliable delivery?

Actually, neither of those are recommended for discourse, with recent developments, email setup is optional, but if you want to allow email notifications, You should use an ESP like Mailgun, sendgrid, brevo, AWS SES etc.