The user can't ask a new question. I'm trying to understand why that is.
It looks like the user tripped a brief throttle, blocking him for one day. He has another question, which was downvoted, closed, and deleted, so that contributed. I don't know the details of the throttling algorithm (I believe it's intentionally kept secret), but I see no question block on this account now. He should be able to ask another question.
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Why am I getting this message?
As stated in the about links on every page, Stack Exchange is a network of question and answer sites, not help forums. This implies that all posts are expected to have some value for later visitors too. To enforce that, and to prevent help vampires making the answerers turn away from the communities, low-quality questions and answers are blocked. This includes posts from:
users who can't be bothered to form sentences users who don't do the most basic kinds of research themselves users who barely even explain what it is they are trying to do An automatic filter is in place to ban questions and/or answers from IP addresses or accounts with a history of extremely poor posts.
To avoid bypassing the filter its internal rules are a secret, but it is partly based on downvotes cast by other members of the communities. If the other members of the site consistently give your posts a low ranking, you should try to identify the reason(s) for this.
Once you have posted too many poorly-received questions or answers, you will be banned from posting more, and you will see the error message.
Are deleted posts taken into account too?
If a post was poorly-received (downvoted or closed), that will continue to count against your account even if the post is deleted! Whenever possible, try to fix posts instead of deleting them.
Additionally, deletion itself counts against questions if less than 30 days old when deleted if others have invested time into answering or moderating the question.
Finally, deleted answers always count towards an automatic ban on new accounts.
It's not a problem to have deleted posts. But if a large percentage of your posts are deleted by yourself or the community, then apparently they are not suitable for the site. Posting them consumes time from users who read them, edit them, or respond to them. Therefore deleted posts have an effect on the filter, among many other factors.
Beware that an account might very well have many deleted posts, including auto-deleted old low-score questions, all of which are only visible to moderators.
Is a question/answer ban the same as a suspension?
No, a suspension is a manual, temporary penalty during which a user cannot ask questions, nor post answers. All other privileges, including commenting and voting, are also revoked by temporarily setting the reputation to 1. Such suspension is publicly visible to other users.
A post ban is enforced automatically, and only prevents posting questions or answers. It is invisible to others.
How do I avoid getting a question ban?
Read the pages in the Help Center, particularly those about asking and the Stack Exchange model. Investigate and search before you ask. Put some effort in your questions.
All questions are expected to have some value for later visitors too. So if many of your questions do not get any answer, are downvoted, closed, or deleted by yourself or the community, then apparently they did not meet the required quality. Be sure to understand why that happens, and learn from that. Don't simply repost the same question again.
If you're not sure what qualifies as a "good question", there are some hints and tips available:
How to Ask from the Stack Overflow Help Center Writing the perfect question by Jon Skeet How to Ask Questions The Smart Way by Eric S. Raymond Getting Answers by Mike Ash To learn about formatting:
Formatting help How do I format my code blocks? Try for yourself in the formatting sandbox How long do I have to wait before I can post again? What can I do to release the ban? How can I reactivate my account?
Automatic bans never expire or "time out." This means that you cannot simply wait for a certain amount of time. If you do not take action, you will never be allowed to post again. The only way for the ban to be lifted is by contributing positively to the site in other ways.
Moderators cannot lift the ban.
Before you do anything else, fix your existing posts! As noted above, down-votes cast by the rest of the community factor into the ban - so the single best thing you can do to get it lifted is to address any objections raised by others. Were your past questions unclear? Did they fail to show any effort on your part? Poorly worded, titled, formatted, and overly long or short? Then fix them!
Note the emphasis on fixing. Do not delete your posts. As explained above, deleted questions (if less than 30 days old when deleted) do still count towards the question ban. Deleting your posts does not help to lift the ban. Only fixing does! Under some conditions you can see a list of your own deleted questions and answers.
If you are banned from asking questions, then writing a few quality answers that get upvoted might enable you to ask questions again. But as the internals of the filter are secret, there is no way to know for sure.
If you really, really think the ban is an error, then email the team directly using the "contact us" link provided at the bottom of every page. But note that reactivation of banned accounts is not a high priority.
Can I simply create a new account?
No. The automatic ban is at a lower level than account.
I'll just ask somewhere else on the SE network, and they'll migrate my question to the correct site!
Migrations are not possible if your account is banned from asking questions on the destination site. The question will simply be closed as off topic, but not migrated.
Does this apply to Meta Stack Exchange too?
Yes, but the threshold of votes in the auto ban calculation is reduced because downvotes can be more common on meta.
My account is in good standing. Why am I still blocked?
The ban also takes in account the IP address. If you browse from a shared computer, or from a location that gives the same IP address to many end users, it's enough that another user who was banned or triggers the ban, will affect everyone else accessing from the same location.
To help rectify this, browse from a different location.