I have emails from one customer where every email received by my Exchange Online (Office 365) account are going to Quarantine. I have other emails from other domains that are not spam also going to Quarantine, too. I had my customer send me an email saying "This is a test", and it was Quarantined. In addition, my customer's domain is not only any spam list. Something is horrible broken on Exchange Online. I can't add every domain to an allow list and I can't predict which domains I will receive emails from. Nor can my customer's go ask every company they email to contact their IT department ahead of time to put the domain on an Allow List. In other words, Microsoft's spam filtering is a business killer. I can pinpoint when this started to the day, March 27th.
So the questions are:
1) What happened to the spam filtering on March 27th where it is now 100% inaccurate?
2) How does a company get their domain off Microsoft's inaccurate spam block list?