Server reachable without credentials (port 25 open relay) returns
{ success: true, warning: 'no_auth' } instead of green success.
Frontend shows red warning: server reachable but emails will fail.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Previously only the password fell back to stored value; username could be
missing if form field was cleared. Now both credentials fall back to the
stored config, ensuring auth is always tested when credentials exist.
Also adds explicit 10s timeouts to prevent indefinite hangs on unreachable
SMTP servers.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
schalli