From Mibbit Wiki
On irc.mibbit.net, to make it so that a person has op on join, you must follow the following procedure. This may or may not work on other servers.
- Ensure that your channel is registered.
- Ensure that the nick the user is using is registered. If it is not, please tell them to register it.
- Either use the proper AOP or Access command. This depends on whether or not you are using the xOP or Access system. By default, the Mibbit server uses xOP.
- Tell the user how to access the power. The user will get the auto-op, or whatever power you give the user, when the user joins the channel while identified (if the use has not used the command /ns set autoop off) or when the user uses the command /msg chanserv op #ChannelName