Microsoft warns that Gmail blocks some Outlook emails as 'spam'

> While Microsoft didn't share the root cause behind Outlook.com emails getting tagged and blocked as spam

Let me guess. These Outlook emails are spam.

I notice nowhere does this article say otherwise.

It seems many domestic hosted smtp servers are served as spam, even after an history of legit traffic. Pure IP SMTP or SPF forbid spoofing with proper analysis of headers, namely we would be talking about pown accounts or servers.

But how to verify that? Only gmail people can tell us. And even then, we would have to trust people which interest is to kill alternative SMTP services.

I tried to forward a message from my gmail account to my Outlook/Microsoft-hosted work account, and found out that Microsoft was silently eating messages it (incorrectly) thought were spam, without notifying either the sender or recipient.

I sympathize in theory but MS is the worst offender in this category.

Cloud based Outlook blocks my mail server's emails, signed by all current bells and whistles, no malware nor spam, ever.

So what? :-)

I have seen a substantial increase in outlook.com spam emails as of a few weeks ago.

Pot calling the kettle black.

Outlook.com still rejects messages from an entire c block if they don't like a particular IP, even when other IPs in that range are not black listed anywhere.

To be fair, things have improved and you now get an undelivered mail notification. Used to be the message would simply disappear without a trace.