Double file extension?

[NTIN Page Guy]

Hello ,

This is the default double file extension finder in MailScanner

# Deny all other double file extensions. This catches any hidden filenames.
deny    \.[a-z][a-z0-9]{2,3}\s*\.[a-z0-9]{3}$   Found possible filename hiding

Why does it catch this file?

filename: TIGER.schedule.gbc1.xls

Sure the file has many periods in that shouldn't be there, but users
are notorious for naming files stupidly.  But the file only has one
three letter extension.

Shouldn't this rule be looking for files that contain more than one 3
letter extension.

Best regards,
Robert B, NTIN                           mailto:pages at ntin.net