> What kind of mail are you sending?
Just personal emails. Volume would be somewhere around one email per month or so.
> Are you getting anything on your abuse@ address?
Nope.
> Are you getting any feedback on JMRP [0]?
That seems to require a Microsoft account and that's something I neither have nor want. I believe sending emails has to work without having to register an account for each provider you're interacting with.
> If all else fails, the mailop mailing list [1] can get you closer to someone on one of these networks to help.
Thanks for the tip, although I'm not sure if I'm the right audience for this list, as I just run a personal mail server with very low volume.
Funnily enough the "Best practices" section of the Mailop website contains a dedicated point (https://www.mailop.org/best-practices/#large-providers-gmail...) stating that there might be unresolvable issues when sending to large providers:
> If you want to send mail to recipients who have accounts at big email providers, be aware that all of the above cannot guarantee that these providers won’t reject your mail, put it straight into recipient’s spam folder or just silently discard it - they just impose their own rules on anyone and you virtually can’t do anything about it.
My guess is, that the reason for the problems is the same as quoted in another comment (https://news.ycombinator.com/item?id=29673347), stating that the mail volume is just too low for outlook.com to establish enough trust in the sending mail server.
If you look around on the internet, there are plenty of other people with the same issues with outlook.com. To me it seems Microsoft is doing something fundamentally hostile to small mail servers there. Interestingly enough sending to Office 365 hosted email addresses works just fine.