==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.0
- Deployed with iRedMail Easy or the downloadable installer? downloadable installer
- Linux/BSD distribution name and version: Debian 11
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I have fresh install iredmail server 1.6 and when i try to send email (to test) on gmail account

i have this message :

<domain@gmail.com>: host gmail-smtp-in.l.google.com[173.194.76.27] said:
    550-5.7.1 [server ip] The IP you're using to send mail is not
    authorized to 550-5.7.1 send email directly to our servers. Please use the
    SMTP relay at your 550-5.7.1 service provider instead. Learn more at 550
    5.7.1  https://support.google.com/mail/?p=NotAuthorizedError
    r3-20020a05600c35c300b003a5ead2cb55si862152wmq.10 - gsmtp (in reply to end
    of DATA command)

I don't know how to solve this problem.

I have anything on postmaster tool

i'm using public cloud offer on OVH.com