We are experiencing problems with email redirects from O365 to organizations that use Sender Policy Framework (SPF) checks to filter spam. O365 redirects emails like it is supposed to, but recieving server rejects them because MS email servers are not allowed to send emails on behalf of our domain. We want to keep sending emails straight from O365, so we should list all Microsoft sending email servers as allowed within our local DNS SPF records.
The problem here is that Microsoft lists all of their IP address ranges and instructs to add all of them as allowed, but it is just not possible to add that many address ranges in DNS. We need to find out what are the address ranges of sending email servers used by Microsoft in Office 365, any idea where can we find this information?
