When I initially installed ISPConfig I elected to set User Prefix to [DOMAIN]. I did so to make my task easier - I figured it would be easier to search for user mailboxes, etc when I knew that the domain name would be a part of the file path. How, however, I'm seeing a drawback to that choice. Specifically, when a customer with a domain name like "myveryowndomainname.com" wants to create a mail user named, for example, "customerservice", the user name they have to enter in their mail client will be truncated; i.e. myveryowndomainname.com_customer. This is not a problem for brand new customers. When I migrate customers from our Plesk server, though, it's an issue. The users will often have their mail clients already set up, and asking them to modify their mail client config can be problematic. I am thinking this would cease to be an issue if I changed User Prefix to [WEB]. My question is, can I change this value in a running server without blowing up current customers? If I change that setting to [WEB] would it leave current customers alone and only affect customers added from now on? I know I could answer this question myself by reading through the source code, but I'm a Perl programmer and PHP is a bit daunting yet.