Why when I reply to my e-mail on my phone does it not have paragraph form?

When I reply to an email on my iphone does it just keep writing across the screen and not write in paragraph form so I can easily see the text that I wrote? Please advise. Thank you.

It goes like this......................................................................and keeps going across the screen

when I want it to do this:

I am going to the mall

today and blah fdjsalf

fdjaslfjdslfjsdaljfldjffjldasjf

fdsjflsdjflsdfjlsjflsdjfljfsdl

ldfjsalfjsdlfkdskfjldsfdsljfl