Do all IRC servers send 005 RPL_ISUPPORT?

Question

This numeric isn't part of RFC 1459, but I would like to be able to use it in order to properly stack and unstack modes in an IRC bot. Are there any mainstream IRC servers that don't send this?

Answer 1

It's an optional recommendation to the spec, meaning that people who write clients must not rely on the server always sending a 005. So you can either make it an optional optimization for mode stacking/unstacking, or make it so your bot only works with servers that send a 005 on connection processing.

That being said, I don't think I've ever used a mainstream IRC network that didn't send an 005 during connection processing. I know that's not saying much, and I don't even have any data to back that up with.