Explanation

This is a common issue with Office 365 / Hotmail / Outlook. You’re in good company in their spam folder. To test out delivery to their service, we created an Office 365 account ourselves. On first login, we found an email that they sent us welcoming us to the service. Guess where that email was? The spam folder. See for yourself:

We wish we were lying about this.

How can you expect any consistency in arriving in the inbox when the people who made the inbox can’t even get their emails there? You can’t, but there are things you can do to help your chances.

Do your best

You do your best by making sure that you get a 10 out of 10 score from mail-tester.com. It’s simple: Go to mail-tester.com, copy the email address given to you, send an email to it, wait a few seconds, then click the button to check your score. We can’t help your content or domain reputation, but your DNS can get a 10 out of 10 by using our DNS tutorials.

Report it as a false positive

Microsoft has an article published about reporting false positives to them:
https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/report-false-positives-and-false-negatives?view=o365-worldwide

“It’s your dirty IP reputation!”

We’re going to get this a lot so we might as well publicly address it. We have no evidence that our IP reputation increases the chance of spam folder delivery with Hotmail other than hearsay and theoretical correlation. Here are the reasons we refute this accusation:

First: Microsoft SNDS and their staff agree, repeatedly, that our IP reputation is flawless with their systems. We receive zero complaints through their SNDS program.

Second: If someone out there maintains their IP reputation more militantly than us, we’ll buy them a house. They don’t exist. Our monitoring, alerting, and human visibility over all of our systems are infinitely superior to “just file a complaint and we’ll take a look within the next 30 days” gold standard of the industry.

Third: We can deliver email, through our IPs, to inboxes at Microsoft hosted services consistently.

From where we sit, all of the evidence points to the contrary. If you have factual information that goes beyond the extent of “I sent from here, inbox. I sent from you, spam folder” (correlation does not imply causation) please bring it to our attention via support ticket.