Currently testing 30-day eM Client trial. As to searching in attachments, it looks like correct search of some text string is performed in PDF, but not in MS WORD.
I must point out, that text string is not in English, but in Cyrillic. Probably some time needed to index imported e-mails, I am not sure. Please advise. MS WindowsLiveMail, my current e-mail client, searches attachments OK. Thank you!