[Jellby]

In my latest ebook (to be uploaded soon) I use <blockquote> for letters inserted in the narrative, with offset left margin (but not right, to better fit narrow screens). Printed books would use both left and right offset, and/or smaller type. I also use:

em, span.foreign, span.title {
  font-style: italic;
}

with:

Hubert Sand never <em>wore</em> this dressing-gown.

There is our <span class="foreign" xml:lang="fr">jeune premier</span>, Mr Knight

a burlesque of <span class="title">Hamlet</span>.

<em> is for emphasis, not all italics are emphasized. I could have used <i> instead of <span>, but that's less semantic, and I'm specifying the style anyway.