Unfortunately, there is no way to discover the specific reasoning that your message was marked as spam, although it is a better sign that the message was marked as spam instead of blacklisted showing that the server itself is not blocked.
A message can be marked as spam for several reasons. Most commonly, because something in the message itself triggered the spam filter. Other times, if many individuals have marked emails from a particular email address or domain as spam, it can also cause this. Unfortunately the only people who would know the true reason why the message was marked as spam would be the scanning provider, in this case Microsoft SmartScreen.
There are a few things you can try. First, try sending a message to the same recipient with different information. Simply an email that says "test" will do the trick. If it goes through, then you know that the message that was previously sent had some content in it that was seen as spammy. If that doesn't work, try sending some content from another email address. Its possible that they see that email address as spam due to previous activity. Finally, try sending the message from a different domain entirely.
Another way to show them that you are legitimate are SPF records. Try enabling SPF records on the domain and see if it goes through. SPF records can take up to 24 hours to propagate.
hi jeffMa ,
i have the same problem , i send a simple email different information Simply an email says "test" as you tell me , there is the same problem
now , i will try the SPF records