If you haven't done this yet - start with the outlook postmaster
troubleshooting documentation and open a support ticket with them.

https://sendersupport.olc.protection.outlook.com/pm/troubleshooting.aspx

Matt

On 2021-03-09 7:07 a.m., sam@circlenet.us wrote:
> You are not alone sir, for reasons as yet unknown outlook.com has
> recently started blocking my range as well.
> If I make progress in contacting someone with clue I will pass that
> information along privately.
>
> Sam Moats
>
> On 2021-03-08 16:18, Dan Walters via NANOG wrote:
>> Good afternoon,
>>
>> So I'm looking for a contact at Microsoft in particular someone on the
>> outlook spam protection/prevention team to assist us with a IP block.
>> I have allready signed up for SNDS and there is no data given .
>> Please feel free to contact me off the list.
>>
>> Best Regards,
>>
>> Daniel Walters