Microsoft Defender Blocking My Website

Hi folks, 

I apologize in advance if this isn't the proper forum for this type of question but I would appreciate any direction or input you might have.

I am having an issue where my some (but not all) of my company's emails and web pages is being blocked by Microsoft Defender for Office 365. I have signed up for their junk and spam alerting service and not gotten anything back. Ideally I'd like a way to submit a claim to have my website globally whitelisted.

It is incredibly inconvenient and honestly embarrassing to ask your customers to whitelist you in their anti-virus software in our security related industry. 

Any help or direction appreciated, thank you.