Email sending do not work

[admin]

SSL certificate is for the server mode whereas sending email is done in client mode. Enabling less secure apps won't do anything because the script fails before the login happens. Wantread means that there's not enough data (or no data at all) to be read from the server. During normal operation at this point the SMTP server sends a greeting line to the client.
Alternative solution is to use a mail sending service that has API so you can send via HTTPS requests instead of SMTP. Try https://sendgrid.com/ or https://www.mailjet.com/