I am facing this issue many times. when i place any order from front-end side, the order placing successfully and it's show order number. but when i check this order on my back-end admin it show this (The order confirmation email is not sent) message. and nothing on my mail box. i send this order mail manually pressing "send email" button.
- Other mails are working fine(REGISTRATION,SUBSCRIPTIONS AND OTHER ORDER STATUS MAIL ) and as a time. but just only order confirmation email is not working.
is that any setting from back-end to solved this issue?