@codinghorror thanks for the response. Yes, I don’t see a problem with safety. It appears that those old accounts with imported emails can be deactivated without any problems. But that leaves several hundred accounts on the user list, many as much as 22 years old. These old accounts display as greyed and gravitate to the bottom of the user list. Is there another option I may be missing? Deactivation is doable but it seems to leave unneeded and unwanted baggage and complexity. Could deactivated accounts be moved to a deactivated user list? I would think this to be a common issue with all forums.
EDIT: I forgot to mention a similar situation likely occurs when a member quits or is deceased which must happen often. Yet the only option is deactivation.