PHP - mailing list

Does anybody know how to detect email address that are no longer operational
using PHP the IMAP functions etc. There are over 1000 addresses subscribed
to the Sailwave mailing list and many of them are no longer valid; I'd like
to auto remove such entries. I can think of a way to do it but it's a
clunky/ugly and not full proof solution - Yahoo groups seem to do it OK with
their concept of "bouncing" email addresses.

Regards,
Colin J
www.sailwave.com

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