Re: Fully spam/virus filtered mail, and reliable outbound relay

From: Frank Slootweg (this_at_ddress.is.invalid)
Date: 06/11/04 

Date: 11 Jun 2004 15:21:15 GMT

Leythos <void@nowhere.com> wrote:
[deleted]
> I think you are going to find that the block SMTP out of their network
> and into their network so that home users infected computers don't start
> sending spam/virus infected email directly from their PC's.
>
> In a lot of cases, a virus will have it's own SMTP server so that it can
> send directly from the infected PC to the public - if they block
> outbound SMTP except from their server it means that those infected
> email don't make it out.

  That argument was given by my ISP, Wanadoo (NL), and swallowed by a
lot of people. I think it is (mostly) non-sense, because many viruses do
not have a SMTP server per se, but a SMTP engine. Some of those engines
just use the local (i.e. of the infected machine) configuration to
determine the default mail server and use that. For most people the
default mail server will be their ISP one, i.e. the *non*-closed one. So
for those viruses, the virus can happily continue to send itself to
other potential victims. Sadly all the readily available references I
have are in a Dutch group of my ISP, i.e. not in English and not
available outside my ISP.

  IMNSHO closing outbound port 25 is only hindering legit users and not
solving any problem (which the virus-writers/spammers can not quickly
work around). For example my <user>@<not_my_ISP>.<tld> mail is sent from
<server>.<my_ISP>.<tld>. IMO, *that* (i.e. legit mail) looks like
(potential) abuse.

Relevant Pages

  • RE: SMTP Stopped working
    ... I think we need to find out whether your ISP is actually going to forward ... to the intended relay server. ... You mentioned that Outlook and Outlook Express work. ... When testing with Outlook Express are you providing the ISP's SMTP server? ...
    (microsoft.public.exchange.connectivity)
  • Re: SBS2003 - Exchange config
    ... > forget about forwarding all of your email to your ISP? ... > inbound email will simply sit on the ISP's mail server ... >>SMTP smart host does a lot of other things, ...
    (microsoft.public.windows.server.sbs)
  • Re: Is this to say email source is not all it is cracked up to be?
    ... power to force the relevant ISP to look it up. ... because these aren't SMTP connections. ... email is the IP address of the web server providing this service. ... Lastly, once they find the person, there may not be laws in that person's ...
    (microsoft.public.security)
  • Re: Is this to say email source is not all it is cracked up to be?
    ... > power to force the relevant ISP to look it up. ... because these aren't SMTP connections. ... > SMTP email headers can be forged, IMHO this isn't the largest problem here. ... > email is the IP address of the web server providing this service. ...
    (microsoft.public.security)
  • Re: Need some (lots) of help on SBS 2003
    ... with 3 PCs connected to an SBS 2003 server. ... turned off the SMTP service at least to get a bit of head room. ... ISP provides email via POP.blahdeblah.com & SMTP.blahdeblah.com. ... What I want to do is either a) change the exchange server to use the ...
    (microsoft.public.windows.server.sbs)
Loading