My client, has SPF and DKIM set up correctly but is having multiple failures when emailing certain organisations when emailing multiple people in the organisation. Recently we asked the Exchange administrator (who identified this as the issue) to whitelist our domain but obviously it's not always possible or identifiable in advance.
If I set up DMARC on the domain does it do anything else other than report on deliverability issues? And do I have to set it up through a third party (eg uriports.com)? or is it possible to set it up on our server?
Maybe I should say these are not bulk or unsolicited mail, they are generally transactional emails with multiple people (eg 3) in an organisation.
It was reported that this is a recent default setting on Office365 mail servers. Does anyone have any more information about this?