Every ticket for a particular user goes to Spam. Is there a place where we can “clear” the user's email?

There are three ways by which a ticket leads to the Spam folder -

• Manually marked as Spam by an Agent. 
• A ticket marked as Spam by an Automation rule such as the Ticket Creation or Ticket Updates. 
• Any ticket raised by a "deleted contact" in Freshdesk would go to Spam automatically.

To have this resolved, kindly ensure that there are no automation rules that would mark tickets as Spam automatically and also make sure that the contact is restored from the Deleted list under the Customers tab.

If you believe that a ticket was not marked as spam from the customer end, you can navigate to your spam folder, unspam it, and check how the ticket was marked as spam in the "Show activities" option in the top right corner.