I found this thread, that referred me to the rule:
http://www.eqemulator.org/forums/sho...ght=chat+error
Setting that rule to false still doesn't let a character chat in ooc, and the red message "Please wait until we reconnect you with the Universal Chat service..." is still displayed.
That said, ooc seems to work now.
What is the "correct way" to fix the chat key mismatch error?