Broken HELO [was: tlug: Naive VM question]

[Kei Furuuchi <kfur@example.com>]

Stephen J. Turnbull writes:
 > (3) I don't know what TWICS does if the PTR lookup of TCP connection
 >     IP address doesn't match the HELO address; I know that many ISPs
 >     forward those with "may be forged" tags on them.  This is clearly
 >     inconsistent with refusing purely on the basis of a broken HELO,
 >     though.  It's far more likely that a broken HELO is due to poor
 >     configuration (often of the DNS) or a change in the DNS than to
 >     intent to launder a spam.  A HELO address with a MX or A record
 >     that doesn't match the PTR of the TCP connection is far more
 >     likely to be spam, but even there the majority of mismatches occur 
 >     because of multihomed domain names.
 > 
 > (4) I have had mail to TWICS refused because my local DNS was broken,
 >     resulting in delays of hours, and in one case more than a day.

I found another mail server which rejects mails due to the reason
above.
So I thought setting:
	define(`SMART_HOST', smtp:"local ISP mail server")
in sendmail.mc is an answer because even if HELO is still broken, the
local ISP mail server accepts the mails and relays, if they are
delivered from within ISP subnet. I don't know how the mail server
verifies.  As long as /var/log/mail.log is concerned, the mails are
accepted. But, I have a feeling that the destination mail server still 
internally rejects and I don't know the mails are rejected.
So I want to know if above assumption is true.
Also Netscape browser's mail function seems to be able to use ISP's
outgoing mail server beyond its subnet. I wonder how it is doing.

Regards,
Kei.
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