Did you send out mails directly from your ISP? (Than I could unterstand Microsoft.) Only your MX must send out mails. And only it should be in the SPF record.
It would be crazy of Microsoft to look at all Received-Hearders and want everything mention there in the SPF record. If that is what really happens, than you should exclude this information from the header.
(mask-src on Opensmtpd. Pretty sure Postfix has that option to, but haven't used it in a decade, so I can't tell you the syntax.)
It would be crazy of Microsoft to look at all Received-Hearders and want everything mention there in the SPF record. If that is what really happens, than you should exclude this information from the header. (mask-src on Opensmtpd. Pretty sure Postfix has that option to, but haven't used it in a decade, so I can't tell you the syntax.)