DSN code 5.7.1 error in O365 emails

my user received the following error message when submitting claim from our inhouse system

mailto:eclaim@goldenvillage.com.sg
Your message couldn't be delivered because there is a partner connector configured that matched the message's recipient domain. The connector had either the RestrictDomainsToIPAddresses or RestrictDomainsToCertificate set.
For more information about this issue, see https://go.microsoft.com/fwlink/?LinkId=389365.

PU1APC01FT038.mail.protection.outlook.com gave this error:
TenantInboundAttribution; There is a partner connector configured that matched the message's recipient domain. The connector had either the RestrictDomainsToIPAddresses or RestrictDomainsToCertificate set [PU1APC01FT038.eop-APC01.prod.protection.outlook.com]