[exim] HELO delays

For some months now we have used a HELO ACL to delay by
35 seconds all connections with suspicious looking HELOs.
This is very effective at reducing the amount of spam
that our servers receive, while not preventing "real"
email getting through, because much of the current
spamming software seems to drop the connection during the
delay period.

As our mail volumes get higher, however, I am beginning to
be concerned about the load that all these delayed
connections will place on our servers. At the moment it
does not appear to be an issue, but I am looking for advice
on whether or not it is likely to become a problem.

Regards

Clive Goodhead
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Cornwall Internet Limited
Registered in England, registered number 3387326.
Registered office: Montaza, Fore Street, Goldsithney,
Penzance, Cornwall, UK.
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