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?

closed as too broad by Xander, John Deters, Matthew, Neil Smithline, LvB Jun 2 '16 at 9:13

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    Perhaps your ISP's spam filter was off for a few hours? But really, we can't possibly know why. All we can do is guess, which isn't really going to help you or anyone else. – John Deters Jun 1 '16 at 15:47
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    That might be the case, but I wouldn't know that ahead of time (i.e. without asking the question) and there may be some kinds of responses that are actionable. – Nytik Jun 1 '16 at 15:59

The most reasonable explanation is that your email address recently ended up in a email list used by spammers.

How could this happen? There are at least three possibilities:

  1. you recently subscribed to a website, who secretly "shared" email addresses with shady organizations;

  2. you subscribed (perhaps a long time ago) to a website which was recently breached, and the resulting email/password dump circulated in underground communities;

  3. someone directly gave your email address to spammers, as a prank. Unfortunately, there are individuals and websites devoted to this ridiculous activity.

  • Some of the commenters on this post by Troy Hunt mention getting an influx of spam related to the recent MySpace breach. Coincidence? I think not. – Philip Rowlands Jun 1 '16 at 15:56
  • Thank you, though I wonder, does this explain the unfiltered part of the question too? – Nytik Jun 1 '16 at 16:00
  • @Nytik I guess not. Spam emails don't get filtered or unfiltered because of the source of the "leak", so to say. It has a lot more to do with writing more sophisticated emails which don't trigger the spam alerts or, as John Deters suggested in a previous comment, with a possible downtime of your ISP spam filter. – A. Darwin Jun 1 '16 at 16:04

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