Emails Randomly Reaching Destination

Glenn Steen glenn.steen at
Fri Mar 19 16:08:12 GMT 2010

On 19 March 2010 16:02, Alex Neuman <alex at> wrote:
> RBL's started out as "ip only".
> There are some new RBL's out there that will work with domains.
> On Mar 19, 2010, at 9:50 AM, Vernon Webb wrote:
>> Is the domain name checked at all when receiving emails or is it based
>> solely on the IP address of the originating IP that determines if it is
>> RBLed or not?

If you look at the relevant RFCs (5321, 2821, 1123 and 821), you'll
see that the reasoning there is more along the line that you MAY
lookup the reverse, but MUST NOT reject based on that info... Wouldn't
stop some from doing so anyway, but... Unless the "other firms
blacklisted servers" also are some kind of smarthost (or similar),
they shouldn't come into play.

-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se

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