To help channels with moderation and engaging viewers sent by another stream:

I propose that the /raid and /host commands accept a short Optional text after it to indicate their raid or host message, and a special chat badge be granted to visiting chatters for a limited period of time (5-10 minutes) who come in after a host or raid from another channel they were watching, and Mouse hover-text over the raid badge and an IRC Tag visible to moderation bots be added to the raiders' chat messages indicating which raiding channel a user last came in from.

The badge would help make raids stand out in the chat and allow for streamers to configure channel moderation bots to make filters and chat rules more intelligent by providing special exemptions for 'friendly spam' from friendly raiders - while most of the time (outside legitimate raids) being very strict against probable spam from new or first-time chatters to a channel.

For example: The streamer's channel moderation bot could detect chat messages which simply contain Raid message text, and exclude those from spam detection policies for duplicated messages or repetitive message text.

Twitch could also consider extra moderation settings to exempt raiding chatters from certain policies such as /uniquechat for a raid of certain size, or /followers, if the Raiding chatter satisfies that condition with respect to the channel the raid is caming from.

In addition the raid "message" could appear in the receiving chat as an automatic chat message by the streamer along with the raid and allow the raid or host action to be moderated by the receiving channel.

For channel management purposes: I would suggest that chatters' raid badge expire after 5 minutes, or an amount of time configurable by the stream receiving a host/raid, and in the case that the broadcaster who sent the raid is placed on a /timeout or /ban before visiting chatters' raid badge expires: All of the raiding chatters would be blocked as a group from sending messages to the chat until the raid badge expires or timeout of the raiding streamer is removed, Except of course any chatters who had subscribed or followed the raided channel before the raid.

In the case of receiving a hostile raid: I suggest the broadcaster who was raided with the /raid command be given an extra command that would redirect chatters who don't follow the channel and who have a particular streamer's raid badge non-expired away from their stream and back to the Twitch front page.

And that the broadcaster who sent the raid have the same capability (In case the raided stream has a bad reaction to it, provide a command where they can withdraw their own raid during that time period, sending their chatters back to the Twitch front page as long as their Raid chat badges have not yet expired).