title: Periodic Office 365 SMTP Send Error Due to TLS 1.1/1.0
body: <p>We have PHP web application that sends SMTP emails via authenticated smtp.office365.com.  This has been working for at least a couple of years.</p>
  <p>We are using PHP Mailer 5.2.  We are forcing the crypto_method to STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT.</p>
  <p>Here's the weird thing.  About 75% of the time it works fine.  The rest of the time it reports SMTP ERROR: Password command failed: 421 4.7.66 TLS 1.0 and 1.1 are not supported. Please upgrade/update your client to support TLS 1.2.</p>
  <p>Registered Stream Socket Transports is tcp, udp, unix, udg, ssl, sslv3, tls, tlsv1.0, tlsv1.1, tlsv1.2</p>
  <p>How is it even possible that it works most of the time.  If it were truly a TLS issue I'd expect it to fail 100% of the time.</p>