Google Workspace SMTP relay (smtp-relay.gmail.com) rejects generic EHLO identifiers such as "localhost", which is Go net/smtp's default. Operators can now set SMTP_HELLO_NAME to a valid hostname so that c.Hello() is called before StartTLS, satisfying strict relay policies. Fixes https://github.com/getprobo/probo/issues/1284 Signed-off-by: Bryan Frimin <bryan@probo.com>