[exim] email and +-extension useful?

Hi!

I just learned that I could use schimmer+extension@??? as email.
Extension changeable for the special case.
Is this practicable for exim 4.5+ and cyrus with sieve?
Any docs about that?

MfG,
Lars Schimmer
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TU Graz, Institut für ComputerGraphik & WissensVisualisierung
Tel: +43 316 873-5405       E-Mail: l.schimmer@???
Fax: +43 316 873-5402       PGP-Key-ID: 0x4A9B1723