Proof of SMTP acceptance (this sandbox → Gmail SMTP, live test just now):
  Host: smtp.gmail.com:587 (STARTTLS)
  Login: support@247techteam.com — AUTH SUCCESS
  sendmail() refused_recipients: {}  (empty = accepted by Gmail, no bounce at SMTP layer)
  Message-ID: <178914175742.18103.7054728962697940107@172.30.1.168>