[exim] Is this true

This is a claim made by Mirapoint in a bulletin put out by UCISA, I am
not convinced that the last paragraph is true, I thought there were
quite a few sites that did not respond correctly to greylisting like
this. Is this just steaming bison poo ??


To verify the sender, MailHurdle looks at the originating IP address and
the From and To addresses in the message. If a particular recipient
hasn’t previously received a message from the sender’s IP address,
MailHurdle sends a temporary failure message back to the originating
mail server using a standard SMTP failure code. If the originating mail
server is a bulk e-mail system, it will generally not resend the
message. Viruses using raw SMTP to send messages will also not retry.

If the message is legitimate, the originating mail server will quickly
retry sending the message, at which point it’s allowed through the
gateway. (According to Mirapoint, there’s one old version of GroupWise
that may not properly retry unless it’s patched, but every other e-mail
server the company has found supports this SMTP command.)


Ron

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Ron McKeating
Senior IT Services Specialist
Computing Services
Loughborough University
01509 222329