PROBLEM:
in-mta1.srv.hcvlny.cv.net #554 5.7.1 Spam detected by content scanner. Message rejected. ##
Emails send to optonline.net users are blocked and not delivered because Optimun server detect a Spam by contect.
SOLUTION:
User was using on her Outlook signature a picture from a public website that has an hyperlink to the site. Removing the link, she was able to deliver the email.
This is the picture and link on her signature: