Microsoft Exchange Public Cloud Contact

Looking for some help from anyone associated with Microsoft's cloud email service. As of last Thursday, customers of Microsoft Exchange Online and other Microsoft email services could no longer send us email. We are not a Microsoft customer, so I'm not sure of how to get help on this. I think I have some guesses about what might be happening, but it's something we cannot fix from the outside. MS needs to fix it Any help would be appreciated. I can supply more details. Did not want to share too much in a public forum. Thanks.