Why do emails from the site go to SPAM?

Question

postfix

Letters go to spam when they are sent from a site of any content! BUT, I send exactly the same letters from Roundcube, and there are no problems.
Here are the logs
1 - sent from the client (not spam)
2 - sent from the site (spam)
Where to dig? Thank you

Answer 1

Because logs are presented in an absolutely unreadable form, I poke at random, the problem is in the X-Mailer:PHP header.