Spam plesk

[BesnierS]

Hello,

I have a rather peculiar problem ...

I have a plesk server under CentOS 6.5 release 12.0.18.

SMTP server is installed postfix.
When I am sending mails from the server to orange.fr Address / hotmail.com they go spam.

But when I use Qmail instead of postfix, shipments of mail server to orange.fr Address / hotmail.com not go into spam and are well received in the box the inbox.

Strange so ...

Any idea?

Thank you.