You can search for specific text using the search field  at the top of the postings list.  Touch the search field and enter some words:

Note that, as you type, the list is filtered to only include postings that contain your search words in either subject line or message body.  Touch and drag in the list to scroll through the matching postings:

If you select one of the postings, you’ll see that text matching the search words is highlighted in blue:

When you return to the postings list you can clear the search field by pressing the clear icon .  To return to the unfiltered list of postings, press the cancel button .