Description:
Adds a new mail forwarding if type is forward.
Input Variables:
$session_id, $client_id, $params
Parameters (in $params):
server_id (int(11))
source (varchar(255))
destination (text)
type (enum('alias','aliasdomain','forward','catchall'))
active (enum('n','y'))
Output:
Returns the ID of the newly added mail forwarding.