Mailing-list topic subscriptions (especially csail-local)

The GNU Mailman mailing-list software we use at CSAIL allows filtering based on “Topics”. In particular, the moderators of the csail-local mailing list encourage people to [tag their posts](https://tig.csail.mit.edu/email-communicating/csail-local/tagging/; this document describes how “topics” relate to tags, and how to filter csail-local mail based on topics. It may also be a useful reference for any other CSAIL mailing lists (or GNU Mailman-managed mailing lists at other sites) that support topics.

A mailing list can be configured by the list admin to support a number of topics, recognized by keywords or phrases in the subject (or some other places). For the csail-local list, the list admins have defined keywords in hashtag format. (See here for the current list, which may be added to from time to time.)

Subscribers can then choose which topics’ messages they want to receive.

Topics vs. hashtags: Topics only map imperfectly onto hashtags; the list software will only assign a message to at most one topic, no matter how many hashtags the author uses in the subject. For more flexible filtering you may want to consider other methods.

Since a message can only be part of (at most) one topic, no matter how many keywords match, there’s a fixed order of priority in the topics. For instance, a csail-local message with the subject line

Subject: #jobs Bad experience at job interview #not-csail #heavy

will be assigned to the #heavy “Topic” — and only that topic — since that’s the highest-priority topic, even though there are other hashtags in the subject line (and #jobs is first). So a subscriber who wants to get messages in the #jobs Topic but not in the #heavy or #not-csail Topics would not get that message. (As far as the list software is concerned, it’s only in the #heavy Topic. See below for how to see the list of topics in order.)

Subscribing to or unsubscribing from topics: You choose which topics to get (or not to get) on the subscriber-options page. (This page also, for instance, lets you choose digest or immediate delivery and unsubscribe.) That page is https://lists.csail.mit.edu/mailman/options/csail-local

The first time you visit the subscriber-options page, you’ll be asked for your email address and list-member password. For the “csail-local” list, the email address will be (and can only be!) the address that HR has listed for you in the Peeps database of CSAIL members. Unless you’ve changed it, you probably won’t know the (randomly generated) list-member password, so you can click the “Password reminder” button down at the bottom of the login page to get it mailed to you. (You can change it, but since you it gets emailed in plain text, it’s really important that you not reuse a password you use for anything important! Your IMAP password or CSAIL Kerberos password, for instance, would be very poor choices.)

Once you’ve logged in, scroll down to Which topic categories would you like to subscribe to?. If all the checkboxes are unchecked, you’ll get everything, but if you check any of the checkboxes you won’t get messages in any topics you haven’t checked. The order in which topics appear in this list (next to their checkboxes) is the priority order in which topics are assigned by the list software.

We strongly suggest that you leave the next option, Do you want to receive messages that do not match any topic filter? set to “Yes”. Otherwise, you’ll miss messages that don’t have any hashtags in the subject, which might be important announcements from TIG or HQ, or about list policy. You’d also miss anything where somebody misspelled a hashtag or misremembered what hashtag to use (e.g. if they typed #political instead of #politics).

From time to time new hashtag recommendations (and corresponding csail-local topics) may be added, list moderators will try to give advance warning to the list when that happens (since people who aren’t seeing all the list traffic won’t see any topics they aren’t subscribed to).