From the way it reads it looks like he is asking how to bulk remove an email address from the archived messages so when they are turned over they don't contain the redacted email address.
I assume it would be embarrassing and/or problematic to share the email addresses of various ambassadors and other government officials in public records. You could also read something nefarious into it if you want.
This whole fishing expedition is hilarious and transparently political. The Bush administration ran private email servers to avoid FOIA requests, then nuked millions of saved emails when his term was up to avoid handing them over. I didn't see any huge circus or massive outcry about that.
The idea that we should be able to immediately read all the correspondence written by any public official also seems silly... it just encourages public officials not to use email. People are allowed to have private conversations. A reasonable compromise might be a time limit... say emails are held sealed for X years after leaving office, then made public?