Protecting Your Email List from SPAM

The Internet is a big marketplace. The ethics, rules and practices about conducting business in that marketplace are still in their formative stages. Many people find it annoying to be added to an email list advertising goods and services, especially when they did not ask to be added to the list and when they find it inconvenient or difficult to be removed from the list. This practice is often referred to as spamming.

Lists that the list server here at NCSU services may be susceptible to spam. To make it harder for a spammer to spam a list there are a couple of things a list owner may consider doing.

1. Make the list hidden
2. Make the list send-by-subscriber
3. Setting a more restrictive subscription policy

Making a List Hidden

Anyone who has an Internet email account may send a command to the list server here at NCSU. How the server handles that command is up to the server administrators and the owners of the lists. One of the commands is simply "lists". When the server receives this command it will return to the requester a list-of-list that are on the server. But it will not return those lists that are hidden. This makes it harder for the list to be found. And without the name of the list, the spammer can not send unsolicited email to the list. The drawback is that it will make it will also make the list harder for potential list subscribers to find. Lists that have a wide general interest topic may find hiding the list a hindrance. The list owner will have to decide which is better for the list.

If the list owner decides the list should be hidden, the command to be sent to mj2@lists.ncsu.edu (mailto:mj2@listserv.ncsu.edu) will look something like this:

approve PASSWORD configset LISTNAME - noadvertise <<EOF
%*%
EOF

approve foobar configset foo - noadvertise <<EOF
%*%
EOF

Appropriate substitutions will need to be made for listname and list's password.

Make the List Send-By-Subscriber

If an owner decides that making the list hidden is too extreme, then another option is to make the list send-by-subscribers. This will make the list server require anyone attempting to post a message to a list have a subscription to the list before the message will be posted. Requiring a subscription to allow posting will limit spam to a list considerably. The spammer will need to subscribe to each list before being able to send email to it.

Should a list owner decide to set this attribute, the command sent to mj2@lists.ncsu.edu (mailto:mj2@listserv.ncsu.edu) will look something like this:

approve PASSWORD configset LISTNAME - access-rules<<EOF
post.
deny, reeply="Posts not accepted by non-members."
!@MAIN>
EOF

Appropriate substitutions would need to be made for listname and listpassword. Using the previous example the command would look like:

approve foobar configset foo - access-rules<<EOF
post.
deny, reeply="Posts from non-members rejected."
!@MAIN
EOF

Setting Subscription Policies

Setting this attribute allows the list owner to control who is subscribed to a list. Granted, in most cases the list owner will probably not know the person who is requesting the subscription, and if a spammer requests a subscription approval will probably follow. The thing is, most spammers will not request the subscription. This would involve too much work since it must be done on a list by list basis, and the subscription would of course be yanked after the first spam. Meaning that they would have to subscribe again, and with a different email address. This provides too little return for work invested.

Should a list owner decide that they want to approve subscriptions, this attribute may be set by sending a command to mj2@lists.ncsu.edu (mailto:mj2@listserv.ncsu.edu) that looks something like this:

approve PASSWORD configset LISTNAME - subscribe_policy=closed

Appropriate substitutions will need to be made for listname and listpassword. For the previous example the command would look like:

approve foobar configset foo - subscribe_policy=closed

Questions or Concerns

Of course, if you have any questions about any of the material on this page please ask. They may be addressed to listman@ncsu.edu (mailto:mj2@listserv.ncsu.edu).

Last updated June 15, 2005 by dlschmid