email notification not work in opencart

hello, recently i have transferred website from amazon aws to hostigner but now face some problem. basically website is opencart and ecommerce when any customer booked any order he not received any order notiification even when i update he not received it

another part is every opencart website given return form option ............ now when i update there anything customer not getting it by email. so kindky fix it.

i will pay u 700