I am trying to send email to all users(AllUser group in AD) in the organisation once an item has added in an document library, but email is not shooting through designer 2010 workflow. But it only able to send by outlook, How to fix this issue? thanks.
Try to create a group --> Add all users i.e. Everyone --> From designer try to send mail to this newly created group.
This should do the trick to send the mail.
SharePoint can't send email to AD group. It can't get all email of all user of AD group, simply. You should use a SharePoint Group and put all your AD user in this group. With Sharepoint Designer you send emails to SP group Member (by iterate the user)
If you realy want to sent emails to AD group, you need to dev a custom Activity for your Workflow.