elastalert: Not connecting to office 365 SMTP server

When trying to use email alerting over SMTP with TLS it gives the following error

ERROR:root:Error while running alert email: Error connecting to SMTP host: [SSL: WRONG_VERSION_NUMBER] wrong version number (_ssl.c:1123)

Settings:

smtp_host: "smtp.office365.com"
smtp_port: 587
smtp_ssl: true
smtp_auth_file: /home/auser/elastalert/rules/smtp_auth.txt

alert:
- email

email:
- "security@anemail.com"