Bad idea.  Any direct access to a .LIST file by any process other than LISTSERV commands/functions is STRONGLY discouraged.  They are binary files, not text, and without knowing all the intricate details you are very likely to scramble things seriously.

To the original question: the postmaster/listowner wildcard CHANGE command, mentioned by WBrown, is the simple way.  You would send:
   quiet change * *@old.uta.edu *@new.uta.edu 
and let the server do what it does.  The processing time will depend on the total number of subscriptions in all lists- it has to find every eligible subscriber entry - so if your site has enough traffic that this would be a problem if the server is busy for a while, send it late at night or very early in the morning, or on a weekend.  Or instead of "quiet change *..." you could use "quiet change listname *@..." to reduce the processing (might be cumbersome if you have lots of lists).

Or go ahead with your script method, but I think a hundred is much too small and will just give you more grief in keeping track of them, do a thousand at a time - if you are giving full email addresses the server can refer to indexes rather than searching and really should not take too very long to process them.  Again, if you do it early on a Sunday morning, probably nobody will notice anything anyway.

>>> "Emsley, I (Iain)" <[log in to unmask]> 12/09/08 8:54 AM >>>
Can you write a script which updates the details in the .LIST files on the server which shouldn't affect the software performance?

Iain

-----Original Message-----
From: LISTSERV site administrators' forum
[mailto:[log in to unmask]] On Behalf Of Young, David
Sent: 09 December 2008 13:50
To: [log in to unmask] 
Subject: Best mass subscription change method

Hello,
   We are in the process of changing where student mailboxes are hosted and, as part of the process, I need to change all of their subscriptions to the new addresses.  Currently, e-mail is being automatically forwarded to their new addresses but that will stop as of the end of the year.  For those lists that are rebuilt weekly based on our accounts management system, this is no problem, but there are about 10,000+ subscriptions that need to be changed for the students where they have subscribed manually.  Since Listserv can do adds and deletes in bulk operations, is it possible to do changes using the same method?  I've written a script that will send batches of CHANGE commands in groups of 100 so that my Listserv isn't completely monopolized for hours on end, but if there's a better method, I'm all for it.  Thanks in advance.

C. David Young
University of Texas at Arlington
Arlington Regional Data Center
Office of Information Technology
200 East Loop 820
Fort Worth, TX 76112
T: 817 272-3152
F: 817 272-0758