I have Exchange 2013 running and did a whitelist like this
Set-ContentFilterConfig -BypassedSenderDomains DOMAIN.COM
I can do a get-contentfilterconfig and see it and all the other whitelisted domains in there. But, the sender server is still getting a rejection. the error is....
Your message was rejected by the recipient email server. Please check the recipient's email address and try resending your message, or contact the recipient directly. For more tips to help resolve this issue, see DSN code 5.1.0 in Exchange Online - Office 365. If the problem continues, contact your email admin.
Just for kicks I checked their server in mxtoolbox to see if its a listed spam server and its not.
the domain sending is ipsusa.com
Where else or why else can there be a setting to check to see why its still blocked?