Users’ inboxes were flooded with spam Monday, an apparent issue with Microsoft Outlook’s spam filters not working.

According to Mashable, the Twitterverse is ablaze with reports of inboxes filled to the brim with spam messages. The emails ranged from random — but not necessarily harmful — emails to blatant phishing attempts.

There does not appear to be an explanation for the issue, nor is there a time frame for when it will be fixed. Mashable reached out to Microsoft for comment, but has not received a response.

We will update this story as more information becomes available.