How to configure postfix to send email from local domain to relay host and back?

Question

I have smtp domain example.com and cloud relay SMTP host relay.cloud.inc. How can i configure and what should i use to achieve next: When i send email from [email protected] to [email protected] email will route to relay.cloud.inc for security checks and go back to my example.com. Is in possible to achieve?

My stack is:

1. Postfix
2. Dovecot (with LMTP)

• I tried to use transport map in postfix, but i achieved email routing loop.

  In file transport set next config:

   example.com smtp:[relay.example.com]:25
  

• I tried send email traffic to custom content filter first, but i dont have needed result, i currently researching this variant.