Trying to use domains.live.com as website mail server

Hello, 

I am running a website, where we use the service of domains.live.com in order to send emails from the site system.

The emails are being sent through our SMTP server of a company that host our site using the live service with our domain in the mail address.

The problem is that our emails are caught at the SPAM folder, even of Hotmail account itself.

The emails consists only 2 lines of plain text without HTML code.

When I try to send the email from www.hotmail.com site interface the email gets directly to the inbox.

How can I solve this problem?

I would be very grateful for any help, 

Best Regards, 

Tamir