If your brand's marketing emails end up in your own spam folder in Outlook, this is likely to cause some confusion and raise questions about the general deliverability.
The consumer domains (that you send most of your emails to) differ quite a bit from Outlook for business. In general, Outlook for business is by default set to be hard on marketing emails—for good reasons. It is a business platform, and you should not be disturbed by emails that aren’t work related.
Most standard settings will “catch" an email if it seems remotely suspicious or spam like. It’s also common that your emails end up in the spam folder if you send multiple test messages to yourself within a short time. This could trigger Outlook's spam filter as it thinks multiple copies of the same emails are sent to your address, which normally means that somebody is blasting emails towards you.
The spam- and sender qualifying filters for Inbox Service Providers (ISPs) like Gmail and Outlook Live have a better understanding for the concept of marketing emails and have more sophisticated segments to understand the communication.
This is what you can do
Talk to your IT department and ask them to add traffic from the sender address you are using for your marketing emails to the allowlist.
Understand your list. Who are you sending to? If your audience consists of consumers, then getting stuck in Outlook for business may not be an issue as most use their private email address for these types of communication.
Analyze opens. Are the open rates where you expect them to be? If so, this is most likely no issue. Are the open rates dropping? Check the open rates for your top 10 domains and see if your rate is dropping there. Most likely, this is the case.
Regardless of the above, you need to reach the customers that use Outlook for business. Before you jump to conclusions because you're not getting your own emails in the inbox, analyze the data. Look into all your best customers that aren't in the top 15 domains. Measure how their email engagement is and act accordingly.