Key: 887add2abe4b450a21f9f250246b6172
Mail sent from: nao20010128@gmail.com
I added “&farced=1” but it doesn’t work, returns null

Try adding the parameter “&farced=1”, added about it in the API documentation of the service.
/api.php?action=getmail&farced=1&id=<required>&key=<required>&type=json

Tested just now-everything works correctly.
Please tell us your key by mail which was having the problem, and also where he sent the email to a temporary email.