What is queued in an email statistic? Unable to check contacts or send email to 15 Queued

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I do not have a queue enabled.

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this query is giving no results found whereas


here I am able to see 15 Queued contacts, but can’t know who are these 15 as the query is not running.

So, I tried to find such a contact manually who did not receive this email and I got those 15 contacts. Now, all of them have this as an event

Now, I don’t know what this means or why is it queued but I am guessing it is because I had a frequency rule set.
But, since I don’t have a queue. I don’t know how to send emails to these 15 contacts as it did not get send on the rescheduled date as mentioned in the image.

And when I try to send them like usual segment email, I am getting no Pending Contacts

2 problems.

  1. query for filter in search not working
  2. what is queue. I have never setup any queue, then why did the message get queued?
    TIA