For iOS 11: Go to Settings -> Accounts & Passwords -> Add Account. For iOS 10: Go to Settings -> Mail -> Accounts -> Add Account. For iOS 9 or earlier: Go to Settings -> Mail, Contacts, Calendars -> Add Account.
Tap Other -> Add Mail Account.
Enter your name as it should appear in the From field. Description can be anything which helps you identify your account. Tap Next.
Choose IMAP or POP. Under Incoming Mail Server section, enter your Host Name as mail.i.net.au or mail.[YourDomainName]. Enter your full email address for User Name. Enter the same for Outgoing Mail Server as well as your password. Tap Save.