Office 365: Allow Mail Relay Through Exchange Online
KB ID 0001480 Problem If you are used to running ‘on-prem’ Exchange then allowing an IP/Hostname to relay mail (sent mail through without authenticating) it’s handy for things like older multifunction scanners, or applications that need to send emails. Now you SHOULD be sending mail through Office 365 ‘authenticated’, but that’s not always possible. Solution From Office 365,Launch The Exchange admin...