[Klug-general] Mail Servers

[Alan Buchel]

Antispam programs (such as Spamassassin) use a system of scores to
discover spam. A mail will be tested for everything from known spammy
phrases, missing/suspicious headers, to which server it came from. To do
this your mailserver is checked against IP blacklist databases for being
a known spamming address, checked wither it has a reverse DNS entry 
(ensures it is not a dymanic IP) and SPF records matching the domain the
email claims to come from.

If I am interpreting the contents of my /usr/share/spamassassin
correctly, then spamassassin penalises incoming email lacking an SPF
record with a score of up to 2.5. Since some mailservers just bounce
anything with scores between 5 and 10, and /dev/null anything with a
score of 10, so I guess it is important to make sure the domain from
which you are sending will need an SPF record in yourdomain.co.uk's DNS
which reflects the IP of your mailserver.

Alan

On 17/12/10 12:36, Peter Childs wrote:
>
>
> On 17 December 2010 12:11, Paul Littlefield <info at paully.co.uk
> <mailto:info at paully.co.uk>> wrote:
>
>     Set up a 'smart host' in sendmail to use your ISP's SMTP server to
>     send mail.
>
>     e.g.
>
>     define(`SMART_HOST',`[auth.smtp.1and1.co.uk
>     <http://auth.smtp.1and1.co.uk>]')
>
>     Shout if you want more info or links.
>
>     Paully
>
>
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>     Kent at mailman.lug.org.uk <mailto:Kent at mailman.lug.org.uk>
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>
>
> Thats what I'm doing currently. (Except I'm using Exim) the issue is
> that certainly 1and1 limit you to 1 email every 10 seconds (which is
> not really very many for a peak load). I've seen similar limits from
> most other ISPs
>
> Trying to get your reverse DNS to match is a pain, Would using a
> shared hosting supplier fix this issue?
>
> My reading is that part of the problem is the need for SPF records.....
>
> Peter.
>
>
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