My wife and I were denied boarding for our flight from Tulsa to Abu Dhabi. The agent said that we needed to provide documentation showing and e-visa number for entry into Abu Dhabi. A visa is granted for US Citizens when they enter the country, not before, so we could not provide what what demanded. We complained to Delta about being denied boarding and were essentially told that since we didn't provide the documentation requested by the agent, he was well within his rights to deny boarding. We were able to reschedule our flights for the next day and no-e-visa number was required for boarding. Delta maintains that they did nothing wrong and it is our fault we were denied boarding.