I'm pretty sure that using this will cut down on the email volume related to the changes :-)
Only some things can be updated in bulk. The basic approach: Start with some "filter" that selects the issues you wish to update. Then, on the page which lists the issues, you can right click the little gear-wheel in the upper right part of the screen and get the bulk change option. More info: https://confluence.atlassian.com/display/JIRA042/Modifying+Multiple+('Bulk')+Issues <https://confluence.atlassian.com/display/JIRA042/Modifying+Multiple+%28%27Bulk%27%29+Issues> -Marshall
