Blocking bad HELO ( and Netsky virus )

[Postfix-taa <postfix-users@xxxxxxxxxxxx>]

Good evening list ..

Apparently, the NetSky/D virus is always using the recipients domain
name when HELO'ing to my MTAs.

Creating an access-table with my domain names and adding a
check_helo_access line to my smtpd restrictions seems to get rid of the
virus:

--smtp_helo_blacklist--
<my-ip>		554 That's my name
<my-hostname>	554 That's my name
<mydomain1>	554 That's my domain name
<mydomain2>	554 That's my domain name

-----------------------

--main.cf---
smtpd_recipient_restrictions = 
	..
	..
	check_helo_access hash:/etc/postfix/tables/smtp_helo_blacklist
	..

------------

..and of course making sure that parent_domain_matches_subdomains does
not include smtpd_access_maps :=)

So, besides from rejecting the NetSky vira at the smtp level, I also got
myself a pretty reasonable anti-spoofing setup ( at least for the HELO
part ).

Are any of you guys using the same kind of blacklisting ? Am I breaking
something with this approach ?

Thanks

/Torben