smtp setup of go dadyy or hostinger mail on digital ocean

Hi, i have website, where my email sending to my coustomer s is not working , i bought a go Daddy and hostingger email, but it's not delivering to my costumer May it's the problem of GoDaddy you malis or may be of code, i am searching for a developer who can fix it In limited time A expert php developer required. you only have to setup all and check code and make required chnages.