The following article goes over why you would receive a rejection email when updating a knowledge base article.
If you do not meet the correct KB formatting and rules, your KB approver may reject your article and leave comments describing why. Refer to the comments to figure out how to get your article approved.
In order to publish a Knowledge Base article you've checked out, you need to hit 'Publish'. Once you hit publish, you cannot update the article anymore. The article is, at that moment, pending approvals for publication. If you wish to make changes to the article again, you need to hit 'Recall'.
Hitting recall will cancel the pending approvals for publication. They do this by 'Rejecting' the approvals. The author of the KB will get an email stating their request for publication has been rejected. In order to restart the Publish process, hit the 'Publish' button after the new updates are made.
If you still have questions or need additional assistance, please use the 'Contact ServiceNow Team' form.