In general yes, with some exceptions. While the maximum amount of annual leave that can be carried from one leave year to the next is 240 hours for most other federal employees, for postal employees, the maximum is 440 hours for bargaining unit employees and 560 hours for Executive and Administrative Schedule employees.
Further, on separation postal employees can receive a payment for unused annual leave that includes leave carried over from the previous year plus leave accrued in the year they separate.
Also, some postal bargaining unit agreements provide a leave exchange program for covered full-time and part-time regular employees. Under this program, these employees may exchange a certain amount of annual leave for cash.