Re: backup MX need (was Re: Hardware...)
On Tue, Apr 04, 2006 at 10:52:54AM -0400, Dan MacNeil wrote:
> >note that spammers and viruses STILL target secondary/backup MX
> >servers....and 99.9999% of the time your customers only THINK they need
> >a backup MX (mostly because they're relying on obsolete advice from over
> >a decade ago when backup MX servers weren't such a bad idea). these days
> >they are rarely needed, and generally cause a lot more trouble than they
> >are worth.
>
> I'd be curious as to any details on how things had changed in the past
> 10 years.
1. massive increase in the volume of spam and viruses, as well as
dictionary attacks, random generation of bogus recipient addresses,
and trawling of web sites, newsgroups, mailing lists etc (which, e.g.,
wrongly identifies Message-IDs and anything else which *looks like* an
address as an email addresses).
i.e. one backscatter message is not a problem. millions per day is.
2. deliberate targetting of backup MX servers as an attempt to get around
anti-spam rules
> What is listed in our DNS as a backup MX is currently not accepting smtp
> connections, as we don't have recipient maps or any spam filtering there
> and this causes problems....
that's not a bad thing to do - it wastes the time of spamware and viruses when
they try to connect...especially if you have packet filtering rules which just
DROP the connection rather than simply not listening on port 25.
craig
--
craig sanders <cas@taz.net.au> (part time cyborg)
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