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What SCN is doing (why email was blocked)

SCN blocks e-mail from certain sites in order to protect the system.

We do not filter on the basis of content, in part because of lack of useful and acceptable criteria for determining what to block. That the mail from these sites is invariably come-ons for pornography, on-line gambling, free money, or other quite dubious propositions is curious, but that is not why such sites are blocked. In general they are blocked because they have flooded our system with bulk e-mail, which often causes slowdowns or impairments of system services. More particularly, because they have sent us bulk e-mail with false, fraudulent, or misleading headers, or because the site does not accept delivery of return mail.

Such sites are some times identified by mail that individual system administrators have received in their own accounts. But the bulk of such sites are identified by the large surges of undeliverable mail that show up on our mail server. We are unable to distinguish between users on other systems. If an ISP tolerates spammers, the entire site is blocked.

Your site is blocked if, and only if, your mail is returned with a line that says

550 Rejected: spam or spam relay site
550 Rejected: spam; see
Note that mail is sometimes returned for reasons entirely unconnected with spam blocking. Your site has been "blocked" only if your returned message has the line referencing "spam".)

In case you're wondering if your own ISP is telling your messages are rejected, it's easy to check this. Here is a typical bounce (this one for unknown user). You should be able to duplicate this on your own by sending a message to a bogus user at scn:

----- The following addresses had permanent fatal errors -----
(expanded from: <>) 
----- Transcript of session follows ----- 
... while talking to 
>>> RCPT To:<> 
<<< 550 <>... User unknown 
550 <>... User unknown 

If email to SCN is blocked

We are unable to distinguish between users on other systems. If an ISP tolerates spammers, the entire site is blocked. If your site is blocked (and not by error), you need to change your ISP: either reform them, or switch.

If your ISP presents itself as having strict anti-spam policies, compare this claim with the DNSbl reports described below.

While SCN users do have a service to reject mail from specified addresses (sometimes called a "twit filter"), this is not really suitable for blocking spam, because using the service is:

  1. more trouble than just deleting the offending messages,
  2. exacerbates the problem at the system level, and
  3. often extraneous in the case of spam, as we generally block most bulk e-mail sites at the system level within two or three days.

It's more likely that the email was lost or delayed in the internet. If you don't see something show up, the most likely reason is that one server or another is overloaded and taking its time re-transmitting email. Matchnet, PLC (a dating site) tells its users that messages from AOL may be delayed by as much as a day. I've occasionally seen mail delayed longer.

More information than you ever wanted to know about spam is found at our main spam page, .

DNS Blackhole Lists

If you want to go through the trouble of "cut and paste", the data from these lists can be used to show your ISP why their email is being blocked, go to the following section of our main spam page:

site first posted 1-Jan-03; rev 21 Jan 03.

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