We have Office 365 E3 and still use Appriver for Spam filtering. Users are stating that spam is getting through. My question is do I need to configure the Exchange Online server with an Inbound connector for Appriver's IP address. ( Like and on site server?) Will this then only allow email from them to come through and block anyone else connecting to the server?
I have contacted Appriver several times but they do not have any documentation and can not provide any assistance.