A reader writes to ask:

My manuscript contains text messages from one character to another. How would you suggest I format them?

When you present an exchange of text messages in fiction, you're essentially presenting a different form of dialog. As such, if I were doing it, I'd treat the messages the same as any other dialog—except that I'd underline the text instead of enclosing it in quotation marks.

Underlining (or rather italics, which is what underlining in a manuscript indicates) is the generally accepted way to indicate in a story that you're quoting from written or printed material—say, a note or a sign. Or, in today's world, a text message or email.

In fact, I can show you an example from the novel I'm writing now, Waking Vishnu. This passage involves instant-messaging on a computer, but the principle is the same:

The chime sounded again:

am i dreaming

Hasta tried to type, but her shaking fingers turned the words to mush.  She backspaced furiously and tried again:

I dont know.

Then, because that seemed somehow insufficient, she typed:

Sometmies when I deram, I cn fly.

The typos made her wince--as did simply typing with her hurt fingers--but a moment later a response came:

i always can fly

I wish I cd fly, Hasta typed.  Id fly right out of here.

stay in school, chimed her mysterious chat partner.  education gives u wings

She snorted.  Big help, thx a lot.

It might be that, in print, your editor or book designer will decide the text messages should be set in bold instead of italics, or in some contrasting font. That's fine, but it's a decision that'll be made down the road. For your purposes now, though, just underline.