The AllWorldIT email platform employs a form of fighting spam called Sender Policy Framework (SPF). This method allows us to verify the email we receive is from a valid source, valid sources of email for a particular domain are published by the senders' domain administrator, not us. For mail to be rejected by SPF means the senders' domain administrator has explicitly requested this to happen, we are just acting on this request.

Errors receiving mail?
If you are having trouble receiving mail and the error returned to the sender contains "Recipient address rejected: Failed SPF check....", the sender must contact his or her ISP with the error to find out why they cannot send email. To re-iterate, if the email is rejected, the domain administrator of the senders domain has explicitly requested us to verify if the email comes from a valid source, if not to reject it, valid sources are published by the domain administrator, not us.

References:
Official SPF Site
How SPF Works
nformation for Users

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