Can't send e-mails - "Receipient address rejected"

Can't send e-mails - "Receipient address rejected"

Most of the emails I try to send from my domain come back with an "Undelivered Mail Returned to Sender" message. This happens even when I try to reply to messages I received. I know the addresses are correct as they work when I send from a GMail account. Below is an example of a reply I tried to send. Is this something with my setup?

"This message was created automatically by mail delivery software.

 A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.

 

xxxxxxxxxxxxxx@xxxxxxx.org.br Invalid Address, ERROR_CODE :550, ERROR_CODE :5.7.1 <xxxxxxxxxxxxxx@xxxxxxx.org.br>: Recipient address rejected: SPF MAIL FROM check failed