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It works for me.
I found an email in my inbox on my phone, picked a sentence and typed it in spotlight and a few words in, it brought up the email. Am I understanding you correctly? It may be because you're on an iPod Touch and away from WIFI so the iPhone cant access your email offline.
 
I just tried it again, and I have good Wi-Fi and it's not working. I Googled and from what I found said you could search to, from, and subject but not content. Something to do with indexing. I just wanted to check the forum to see what's going on.
 
Spotlight on the iPhone does not search the body of the email. That behavior is normal.
 
Well it's good to know my touch is behaving normally then.

But I can only assume, since there is the option to search "all" alongside "from" "to" and "subject," there will be a firmware update in the future which will allow searching the body of messages.
 
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