I've noticed this also. Sometimes the search "all" does not work but when I find the message other ways the text I was searching for was clearly there.
Are those emails stored locally on the phone or on a server someplace else? Maybe that's the issue - it can't search emails not actually "on" the iphone. Just guessing...
Are those emails stored locally on the phone or on a server someplace else? Maybe that's the issue - it can't search emails not actually "on" the iphone. Just guessing...