It depends on the mailing list's configuration, determined by the mailing list owner. In some cases, anyone can subscribe. In other cases, the list membership is determined by the list owner.
Every mailing list on the server, both public and private, has its own list information page. You can access the directory of public lists at
https://lists.purdue.edu/mailman/listinfo/
To access a private list, you will need to know the exact list name. You can then type the name in the URL like this
https://lists.purdue.edu/mailman/listinfo/listname
(NOTE: listname is the name of the mailing list in question.)
To subscribe to a mailing list, you need to use a Web browser to open the list's information page. Once you have accessed the list's information page, you should see a section that will allow you to subscribe to the list. Enter your email address and name. Once you have filled in the information requested in the "Subscribing" section, click on the "Subscribe" button.
If the list has been set up to require owner approval for subscriptions, you will have to wait until the list owner approves your subscription request.
Otherwise, Mailman will send an email message to your email address. The message that you receive may ask you to confirm your subscription request. This helps to prevent other people from adding you to a list without your permission. When you receive the confirmation request, simply reply to the message. You do not have to add any additional text and you should not modify the subject line.
After successfully subscribing to the list, Mailman will probably send you a welcome message (list owners can configure their list so that welcome messages are not sent). The message will include the URL that will direct you to the list's information page, a URL that will direct you to your personal settings page, and your list password.
Keep the welcome message for future referral! You will need the information contained in it if you ever want to modify your personal settings on the list or unsubscribe.
To unsubscribe from a mailing list, go to the list's information page at
https://lists.purdue.edu/mailman/listinfo/listname
(NOTE: listname is the name of the mailing list in question.)
Under the list's "Subscribers" section you will see an "Unsubscribe or edit options" button next to which you can enter your email address. Enter the email address with which you are subscribed to the list and click on the button. This will take you to the list's "Membership Configuration" page where you can change your membership options, unsubscribe from the list, or request a password reminder.
By clicking on the "Unsubscribe" button, a confirmation message will be emailed to you. The message will have a URL that you can go to in order to complete the removal process. (There will also be instructions on how to confirm your unsubscribe request by email.)
This confirmation step ensures that you will not be removed from the list by someone other than yourself or the list owner.
To edit your subscriber options, go to the list's information page at
https://lists.purdue.edu/mailman/listinfo/listname
(NOTE: listname is the name of the mailing list in question.)
Under the list's "Subscribers" section you will see an "Unsubscribe or edit options" button next to which you can enter your email address. Enter the email address with which you are subscribed to the list and click on the button. This will take you to the list's "Membership Configuration" page where you can change your membership options, unsubscribe from the list, or request a password reminder.
When you have made your changes, click on the "Submit My Changes" button.