Invalid Address, ERROR_CODE :550
Hi!
I sent an email to this address
abadia.vitor@sapo.pt (which exists and is valid ) , but it was returned with the following error:
Invalid Address, ERROR_CODE :550, ERROR_CODE :SPF says you cant (#5.7.1)
What is the solution for this error , since it's an address of a client
I have to contact urgently.
Many thanks!