Zabbix impossible to send email with OVH email pro

Hi,
I just changed my email provider to OVH and I'd like to update Zabbix configuration to continue to receive alerts.

This is my config:

SMTP server: pro2.mail.ovh.net
SMTP server port: 587

SMTP helo: mydomain
SMTP email: Zabbix
Connection security: STARTTLS

SSL verify peer: unchecked
SSL verify host: unchecked

Authentication: Username and password
Username: zabbix@mydomain
Password: **************


With this config I have this error: "An authentication function returned an error"
Can someone help me?

Regards.