Have you checked your mail server is configured properly and it doesn't act as open relay?
> SPF/DKIM no matter
SPF/DKIM is not enough, I needed DMARC and DNS PTR. You need static IP from some serious hosting, make sure IP is not black listed, dynamic home ISP addresses are out of question. Also register with Outlook SNDS https://sendersupport.olc.protection.outlook.com/snds/ , and Google FBL https://postmaster.google.com/ .
It is a lot of hops but I have done it once a few years ago and now it all works fine for me, got 100% delivery for small traffic.
Have you checked your mail server is configured properly and it doesn't act as open relay?
> SPF/DKIM no matter
SPF/DKIM is not enough, I needed DMARC and DNS PTR. You need static IP from some serious hosting, make sure IP is not black listed, dynamic home ISP addresses are out of question. Also register with Outlook SNDS https://sendersupport.olc.protection.outlook.com/snds/ , and Google FBL https://postmaster.google.com/ .
It is a lot of hops but I have done it once a few years ago and now it all works fine for me, got 100% delivery for small traffic.