This guide will walk you through the No-IP POP/IMAP mail setup on Apple iPhone or iPad. Managing, adding, and removing email accounts on an iPhone or iPad happens in the iPhone Settings instead of the Mail app.
Step 1: Open Settings and scroll down to select “Mail.”
Step 2: select “Accounts.”
Step 3: select “Add Account.”
Step 4: You’ll see a list of all of types of mail accounts you can create on your device. You’ll want to select “other.”
Step 5: Under MAIL, select “Add Mail Account”. 
Step 6: You’ll be in the New account screen. Enter your name, full email address and password for the email account. The description field can be filled in as you see fit.
Step 7: After hitting “Next” you will need to enter in our mail server information. You will have the option to select either IMAP or POP.
Example “you@youremailaddress.com.” If the password field is not filled in, enter it again.
Step 8: Once you hit “Next,” it should verify the account and then give you options on what applications you can use with your mail protocol of choice.
Once you’ve saved, you are all set! You successfully set up IMAP or POP on your iOS device.