Our IP block at Linode has been placed on a blacklist for Hotmail infrastructure. This does not affect Office 365 users, even though they use the same infrastructure. I have a ticket open with Linode so they can open a ticket with Microsoft to address this, but delivery to this service has been persistently problematic and unreliable so even once service is restored I would recommend changing your account email to another provider.
As a reminder, any account which is bouncing email will be disabled (as is an industry standard to prevent blacklisting). If you have an issue getting into your account you can contact the admin team for assistance.