Squirrelmail error upon login: Create “sent-mail”, Invalid mailbox name

Solution If you receive the following error message in the left menu of Squirrelmail after you login:

“ERROR: Could not complete request.
Query: CREATE “sent-mail”
Reason Given: Invalid mailbox name.”

This usually means that your configuration file(s) have been damaged and need to be recreated.  You can fix this by doing the following steps:
Edit the below file
/usr/local/cpanel/base/3rdparty/squirrelmail/config/config.php and change the below line as per given below:
$default_folder_prefix          = ‘INBOX.’;