I use the email marketer software from Interspire for my mailing lists and one week, yahoo.com bounced several hundred addresses. I knew most of the addresses were valid because one of the bounced addresses was my own, plus the bounce rate was 20x higher than normal.
Unfortunately, there is no way to bulk undo the bounce status in Email Marketer. I could edit each subscription manually but that would take "forever". I looked at the database in MySQL and saw that I could change the 'bounced' field to 0 to make the subscribers active again.
I used this SQL query to see all of the yahoo addresses and try to identify the bounced value that represented the subscribers who were bounced on the date in question:
select * from `db`.`email_list_subscribers`WHERE `domainname` = "@yahoo.com"
Once I decided on the date value to use, I used this query to look over the records that I wanted to update:
select * from `db`.`email_list_subscribers`WHERE `bounced` > 1351821100 AND`domainname` = "@yahoo.com"
Satisfied that the list included only the subscribers removed on the date in question, I used this query to change the bounced field to 0:
update `db`.`email_list_subscribers` set `bounced` = 0 WHERE `bounced` > 1351821100 AND `domainname` = "@yahoo.com";
This query did not change the bounce counts in the statistics, it only set the affected subscribers back to Active.