There are two ways to do this. If you are interested only in a particular person's subscription date, issue a QUERY listname FOR userid@host command for that user.

If you want a complete list of people on the list with their subscription dates, issue a REVIEW listname NOHEADER BY DATE command. This returns a columnar list of users and subscription dates.

Note that this command (like all of the REVIEW commands we have mentioned above) does not return data for users who are set to the CONCEAL option. Also, if a person subscribed to the list when it was running under a (much) earlier version of LISTSERV, the subscription date field will contain "[UNKNOWN]", as LISTSERV did not log that data prior to version 1.8d.