Redmine

Sometimes I need to do some large ticket-maintenance tasks, like moving bunch of tickets from one project to another, or so.
It works great, but it has some disadvantage - every time I do this, all my colleagues are flooded by large wave of emails (ticket updates), because they are watchers.
It would be nice to send just one email, but I guess this will be not so simply, because there are different watchers in different tickets, so it can't be solved by just one email.
But one feature can help - to have ability to "[x] Disable e-mail notifications for this mass update" - so just one checkbox in form for editing multiple tickets at once, which will disable email emitting for current mass-edit.