Spam not forwarded to Spam folder

Why do some emails that I receive classified under the SPAM flag go to my inbox and are not forwarded to the Spam folder? Note: There are no filters to keep this or other classified emails in the inbox.

X-Spam-Flag: YES
X-Spam-Level: *****
X-Spam-Status: Yes, score=5.6 required=3.0 tests=BAYES_50,DKIM_SIGNED,
autolearn=no autolearn_force=no version=3.4.6
* 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60%
* [score: 0.5000]
* 5.0 SPF_FAIL SPF check failed
* -0.1 DMARC_PASS DMARC check passed
* 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record
* 0.0 HTML_MESSAGE BODY: HTML included in message
* 0.0 HTML_IMAGE_RATIO_04 BODY: HTML has a low ratio of text to image
* area
* -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature
* 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily
* valid
* -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from
* author’s domain
* 0.0 T_KAM_HTML_FONT_INVALID Test for Invalidly Named or Formatted
* Colors in HTML
* -0.0 T_SCC_BODY_TEXT_LINE No description available.
X-Spam-Score: 5.6