Can the postal postmark be stamped by itself? Isn't it just a question of putting it in the mailbox?

If you are addicted to postcards, you can put stamps on them when you like them best. The post office provides this service. If it is not dozens of tickets, there is no charge. Another advantage of this is that the quality of postcards can be guaranteed. If you like traveling, buy some postcards issued by China General Post Office locally and put stamps on the local post office. This postcard looks good and has a scenic spot postmark, which will be very memorable.