Mail Servers -- iSeries & not (was: And so it begins...) -- MIDRANGE-L

Roger Vicker, CCP wrote:
> One is where someone (like me) has their own domain and their ISP wants
> triple $$$ to host it as compared to one of the major hosting providers.
> If the user's home ISP blocks port 25, as I have heard Cox and Comcast
> have, then they wouldn't be able to send email from their domain since
> it would be via a "foreign mail server." Yes, the ISP could allow all
> "from domains" through their servers but then the reverse lookup
> wouldn't match and it would get marked as spam. Also, if they let
> everything through what stops spammers, except #2 below? BTW, while
> Sprint was in the pre-paid dial up business they also blocked port 25 so
> badly that you could only send mail via a web client which meant only
> from your Sprint address.

Your ISP's mail server shouldn't care what the "FROM" address is ... so
long as you are an authorized user of their mail server.  This means you
either have authenticated to their mail server or are in a IP block that
is allowed to relay.

The reverse lookup doesn't pay attention to the from address ... it
looks at the IP address of the mail server connecting.  If you sent
through your ISP's mail server as 'roger@xxxxxxxxxx', the destination
mail server would only look at your ISP's mail server IP to see if it's
in the range it doesn't accept.

> Second is a business that has people work at home occasionally. It is
> not often enough to justify a VPN but they need to respond to customers
> and need to use the company's SMTP because the return address is their
> company address. The company exists on another ISP. Home workers are a
> growing portion of the workforce.

This is easily solved using authenticated relay ... I use that with my
own mail server.  When I'm in my home lan, the mail server relays my
mail without authentication ... but when I'm on the road, I have to send
a userid & password (encrypted, of course) before it will relay my mail
for me.

> Instead of funneling everything through the ISP's servers it would be
> better to:
> 1) Educate about preventing open relay.

Open relays are not really the major problem anymore ... it's zombie
PC's that are infected with a spam sending virus ... this basically
distributes the spammers workload to hundreds (if not thousands) of
innocent PC's throughout the net.  *THIS* is why port 25 is being blocked.

FWIW: Some ISP's allow you to request unblocking of port 25 if you can
provide a reasonable justification.  I know it's fairly easy to do with
SBC.  I know a number of people who are running mail servers using SBC DSL.

> 2) Make the ISP have better tracking of customers/times/IPs for
> backtracking.

Agreed

> 3) Backup the education with major consequences.

What kind?

> 4) Make all SMTP server software providers set the initial/default
> configuration as closed with the administrator required to open items if
> they really need it. The "ease of setup" as justification for  having
> the setup start as wide open is pure nonsense.

Actually, IMHO, there should be *NO* default configuration for mail
servers ... it should always have to be built from scratch.

david

-- 
David Gibbs
david@xxxxxxxxxxxx

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