The reminders are sent based on the "dateadd" field in the "lm_users" table. Set that using PhpMyAdmin to a few days ago and the users should receive a few reminders (depending on your settings).
The following query will update all unconfirmed users on bellsouth.net to April 1st of this year. Note that changing this may skew your "opt-in" evidence.
update lm_users set dateadd = '2008-04-01' where cnf = '0' and email like '%@bellsouth.net%';
Alternately you could create a User Selection to group unconfirmed addresses from that ISP, then craft your own "custom" confirmation email. A "Confirm Link" message code should do the trick. You may want to try it with a test address on a test list to make sure it works as expected.
Regards