A mailing list is the name of a single recipient[19] that, when expanded by sendmail aliasing, becomes a list of many recipients. Mailing lists can be internal (in which all recipients are listed in the aliases file), external (in which all recipients are listed in external files), or a combination of the two. The list of recipients that forms a mailing list can include users, programs, and files.
There is one new addition to mailing lists, but it is not covered until Chapter 23:
Extend the use of LDAP to include aliases files so that LDAP recursion can be used to automate mailing list creation via LDAP queries (Section 23.1.2 [V8.13]).
Here, we cover a few of the do’s and don’ts of mailing list management that were omitted from the third edition.
Managing your own mailing lists can become tricky, especially in light of the recent explosion of spam email and the effort and cost of fighting it. In this section, we cover positive behaviors associated with mailing lists that will help you avoid being labeled a spam emailer.
Clearly indicate subscription and management information
Keep messages small
Don’t use the
To: orCc: headers to create listsLet software do the job for you
Boot members who send spam email
Before we begin, however, we need to mention the difference between an “open list” and a “closed list.” An open list allows anyone interested in it to subscribe through some (usually) automatic process. A closed list is intended for subscribers only and is usually tied to some controlled membership mechanism.
In this section, we chiefly discuss open lists, although the lessons taught can often apply equally to closed lists.
Each mailing to a list should contain clear information describing how a subscriber may be removed from the list and to whom to send questions or complaints.
Subscribers must find it easy to unsubscribe for a wide variety of legitimate reasons:
The subscriber’s interest has flagged or the original reason for joining no longer applies.
The subscriber left a workstation unguarded and a jokester subscribed that subscriber.
The subscriber abandoned the email address and someone else inherited it.
The subscriber moved, and the old address could not be forwarded.
Similarly, it is important that the manager of the list is easy to contact, because that person can uniquely fix a number of common problems:
Someone on the list sent a spam email and must be removed from the list.
The mechanism used to unsubscribe is broken.
A member is receiving duplicate messages or omissions.
In general, there are only two places in a message that can contain such information: the message headers and the message body.
Some mailing list software inserts the information into custom
X- headers on your behalf. For example:
X-Unsubscribe: [email protected] X-Owner: [email protected]
Others arrange for standard headers to work. For example:
From: [email protected]
Here, merely replying to this message will get the
subscriber’s comments delivered directly to the list
administrator (see Section 12.1.1
[V8.13] for a
discussion of the -request suffix).
Other mailing list software appends a standard footer to the body of every message. For example:
This list is brought to you by the power of mailing.list.domain. To unsubscribe visit http://www.mailing.list.domain/unsubscribe or send email to [email protected]. To report abuse or problems, send email to [email protected]. In the event email fails you may also telephone +1-800-555-1234 or send surface mail to MailingList, Inc., P.O. Box 555, City, CA 12345
This footer solves most of a mailing list’s needs. It allows the recipient to unsubscribe either via a web site or by sending email to a clearly indicated email address. It also indicates to whom to send complaints and notices of problems. It is vital (and required) that if you send email from your site, you maintain for the user an alias named abuse, which causes mail for that name to be delivered to an actual person. If email fails, there is a telephone number and surface mail address to fall back on.
We recommend that you adopt as many of these techniques as you can. A
recipient should be able to communicate with the administrator of the
list by simply sending a message to the name of the list suffixed
with a -request. Also, information about
unsubscibing should be placed in clear text in the body of every
message.
We don’t show you how to fulfill those needs in this book. There are simply too many public and custom pieces of mailing-list software available. Rather, we leave the details of implementation to the reader.[20]
Many businesses routinely reject messages that contain attachments or accept them and silently strip attachments. Mailing list management should adopt a similar strategy when accepting messages that will be broadcast to subscribers. To protect the recipients of the mailing list, either reject submissions that contain attachments or silently remove attachments (perhaps with an indication of that removal placed in the body of the message).
The method for rejecting or removing attachments varies depending on the type of mailing list software you use; therefore, we leave the discovery of that method up to you.
Some lists discuss matters that, by their very nature, require readers to view or hear examples. For lists that discuss images or sounds, for example, try to encourage list members to send web references instead of imbedding the images or sounds directly into each message. The following lines illustrate one appropriate technique:
I put my latest 3D images up for you to see at http://www.my.domain/3d/bob/newimages. Let me know if you like them.
Here, a half kilobyte message distributes images vastly more efficiently than would 2- or 3-megabyte message that imbedded the images directly inside itself. Because of that efficiency, use of references is kinder on ISP machines, and reduces the risk that the images will be removed or rejected because they are attachments.
Hands down, the most offensive way to
email a message to a
mailing list is by placing all the recipients into a
To: or CC: header, or into
both. Not only will this likely mark you as a spammer, it also risks
that your site will become listed at one or more blacklisting sites.
Never send mail to a mailing list like this:
To: [email protected] Cc: [email protected], [email protected], [email protected], [email protected], [email protected], ... ... etc. to form hundreds of addresses
There are two serious problems with this approach. First, it reveals all the members of the list to every recipient on the list. This violates the privacy of each recipient. Most who join an organization or mailing list expect that their membership will be private and not advertised to others.
Second, messages with too many header recipients (typically more than 25 or so) are consider spam email by many sites. Mailing list messages are not spam email and therefore should never appear to be.
See 13.1[3ed] to learn the correct way to set up mailing lists using sendmail.
As mailing lists become large, or emailings to them become frequent, lists eventually need to be moved from self-serviced lists to fully automated lists. There are three classes of software available for this transition. Open source software for Unix is mature and well written. Commercial software for Unix and Windows is widely available. Commercial services (some free with advertising included in each message) are also available.
A solution suitable to your needs can quickly be found by simply googling for one.
Each subscriber that joins your mailing list should be made aware of your list’s policies from the beginning. One common way to distribute policy to subscribers is to include it in the initial greeting sent to a new subscriber. Another common method is to post it on a web site. Naturally, we encourage you to do both.
Your published policy should include many of the following points:
The mailing list shall not be used to send unsolicited commercial email (spam email) to its members.
Mailings to the list shall remain on topic and of general interest to the list as a whole.
Members shall not engage in name calling, anger, or offensive language. Members shall not post messages to the list that could be construed as defamatory, libellous, or offensive to individuals, organizations, or institutions.
Mailings to members of the list shall be sent directly to each, rather than broadcasted to the list as a whole.
Members who violate these policies shall be removed from the list.
Subscribers whose addresses continue to bounce for over a week shall be removed from the list.
As the administrator of a mailing list, it is your job to police that list. Any time a subscriber sends an offensive or spam email message to the list, you should immediately contact that subscriber and take corrective action. Many administrators will immediately unsubscribe the offender. Some administrators must find other solutions, because members may have to pay to subscribe.
Find out what your rights are as an administrator before you accept the job or before you set up the mailing list. Make certain you can remove offending subscribers in a timely manner to protect the remainder of your subscriber base.
As a courtesy to your remaining subscribers, you should let them know that you handled a certain problem and that the offending subscriber won’t post to the list again.