Waking up this morning, I found a large number of spam emails in my outlook inbox. Typically I never see any spam in the inbox, as it is almost always successfully filtered. Even in the junk box I only typically receive 4-5 emails on a bad day.
These emails started coming in while I was asleep and continued for 8 hours, at which point they stopped abruptly. You can see the exact times (BST) and nature of the emails in the picture below.
What could be the cause of this temporary large influx of unfiltered spam emails?