Everything you posted looks mostly in order,.. Although I’ve never seen a &emailSubject=`Contact (URL HERE)` Are you using the same email account to receive email from multiple websites? Also I’ve never used the &emailFromName=`[[+name]]`
I think you could get the same results from a
&emailSubject=`Contact[[++site_name]] From:[[+name]]`
I would also add a ":stripTags" to the "message:required" line in the &validate string.
message:required:stripTags
As I understand it sometimes the test tags can interfere with validation.
Can I ask what page is "24", if its published and what your "ContactTpl" looks like?