Strange email format attachement encodnig

Here is sample of email attachemt, it opens OK in Outlook express, but i really don't know how to decode this to useful data (it's .csv file) with php?

begin 664 AGI_NAV_PERF_20100107.csv
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M1552"C V+C Q+C(P,3 [3%4P,C4V.#,Y,C<T.T%L;&am开发者_C百科p;EA;GH@4D--($5U<F]P
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*,"XP,"4[55-$"E0[

end

It resembles UUencoding. It's similar to Base64 and quite popular in Usenet. The convert_uuencode() function should be able to read it. (It didn't work for me, though, but it's possible that the file got corrupted when pasting it here.)

Edit: This is UUEncoded content as pointed out by bluebrother in the comment below, not TNEF. Álvaro G. Vicario has it right.

Original (incorrect) answer: This looks like TNEF, Outlook's proprietary encoding method that takes up less space than base64 encoding.

(Hat tip to @Dave Swersky for finding it out in this question)

In the link, there are instructions how to turn it on and off in Outlook.