Date: August 29, 2025
Status: Ongoing
Affected: Email delivery to recipients on Microsoft 365, Outlook.com, Hotmail.com and other Microsoft-operated domains.
Microsoft has erroneously blocked millions of legitimate email servers worldwide, including several operated by some of the largest global hosting providers (Hetzner, OVH, and others).
✅ Our servers and email systems remain fully secure, clean, and operational.
❌ This issue originates from Microsoft’s internal IP reputation system and is affecting clean IPs globally.
Despite all email checks passing (SPF, DKIM, DMARC) and Microsoft’s own SNDS systems confirming our IPs are in normal status, messages to Microsoft 365/Outlook/Hotmail addresses may be rejected with the error:
550 5.7.1 – S3150: Your IP is blocked
This has happened multiple times in recent years, and Microsoft provides no control or direct support for resolving it — nor do they notify affected businesses before implementing such wide-reaching blocks.
We have escalated to Microsoft's postmaster and support teams.
We're also working with server providers to apply pressure through Microsoft Partner channels.
We’re deploying optional filtered email relay services (Proofpoint) for clients who need guaranteed delivery in the interim (ask us if urgent).
If you're experiencing this issue, rest assured:
Your email system is working normally
There is no fault on your account or with our infrastructure
Please create a support ticket here https://www.futurehosting.ie/clients/submitticket.php?step=2&deptid=3
We’ll keep this notice updated as soon as there’s movement from Microsoft.
Thank you for your patience and understanding — this is a frustrating issue caused entirely by decisions outside of our systems or control.