Re: [cobalt-users] Spam blocking

[Jeff Lasman <blists@xxxxxxxxxxxxx>]

On Tuesday 27 January 2004 09:21 am, David Crocker wrote:

> I've heard it claimed that blocking dynamic IP address ranges is a
> bad idea because it will block some legitimate email. I've also seen
> the opinion expressed (several times) that anyone sending mail from a
> dynamic IP address should route the mail through their ISP, not send
> it direct from their own SMTP server. Does anyone here have any views
> on and/or experience of this issue?

The most important issue is really this:

Do you allow your clients to use your mailserver for outgoing email?  In 
other words are they required to use their ISP's mailserver, or do you 
run POP before SMTP, and allow them to use your server for outgoing 
email?

Do you use your own mailserver yourself?

If you allow them to use your mailserver for outgoing email, and if they 
have a dialup connection to the Internet, or a connection to the 
Internet through a dynamic IP address (most DSL and cable-modem 
connections for example) they won't be able to send email through your 
server even if you have POP before SMTP enabled, as the block comes 
before the POP before SMTP checking.

So if you decide to implement one or more blacklists covering dialup 
and/or dynamic IP ranges, be prepared to tell your clients you no 
longer allow outbound email through your servers.

Jeff
-- 
Jeff Lasman, nobaloney.net, P. O. Box 52672, Riverside, CA  92517 US
Professional Internet Services & Support / Consulting / Colocation
Our blists address used on lists is for list email only
Phone +1 909 324-9706, or see: "http://www.nobaloney.net/contactus.html";