I hope I can understand what caused this so it can be prevented from ever happening again. We have a managed server we lease. We don't have access to the system except through ISPConfig. One day last week our customers' email started to bounce. The server admin did something to fix it (and we don't know what), but we had to reset every single user's password on every domain before they could retrieve mail. There is something that preceded this event, and I wonder if it's related? I was having trouble adding an A record and emailed support. They said, "The control panel was looking in the wrong area for new DNS entries. This is now fixed and your A record should be working." Could this fix have precipitated the email problem? Thanks!