On Thu, 8 Jan 2009, Alessandro Vesely wrote:
Setting a matching HELO name may be cumbersome when using NAT, multihomed
hosts, VPNs, and the like. IMHO, checking the domain name should suffice.
Multihomed hosts just need to use a HELO that matches the IP they
are sending mail on. Using a single HELO name with multiple A records
that matches *all* their IPs works too if the sending IP is selected
randomly. NAT and VPN are irrelevant. Just set HELO to something that matches
whatever you are natted to - just like multi-homed.
I don't *require* PTR. HELO works just as well as rDNS (better and cheaper).
But I'll take a valid PTR in place of a bogus HELO to establish MTA
identity. I don't like MTAs that require rDNS/PTR, because the vast majority
of MTAs for small domains do not have a 256 block of IPs, and have to
beg and plead with their ISP for weeks to get rDNS configured properly.
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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