Thibault Martin created an issue #480:
When there are waves of spam on IRC, a popular way to prevent it is to (sometimes temporarily) restrict access to the channel by adding the +r mode so only registered users can join.
When somebody joins Matrix and go to the IRC-bridged channels, they are not registered against NickServ. It means that as soon as a channel is set to +r all Matrix users are kicked from the channel.
There is a way to circumvent that, which is manual registration against NickServ (by PM'ing NickServ from Matrix and doing a registration à la IRC) and then asking the gateway to remember and replay the password (by PM'ing another bot)
NickServ is not that popular among IRC users, but this experience is particularily difficult for newcomers joining through Matrix.
One good solution to that is to quit relying on user registration to prevent spam. One of the most efficient ways to make sure the channels can be browsed by anyone but no spam can be posted is to set the following MODE +q $~a. This allow anyone to join, but prevents all unregistered users from talking, effectively preventing spam.
This can play nicely with Matrix bridges by setting an exception, so by actually setting the following MODE #channel +qe *!*2001:470:1af1:104:*. This will have the same effect as above, except for the users coming from the Matrix bridge. As a result they don’t need to do the NickServ trick which is not very matrixy.
Now that mode can be a bit harder to memorize for IRC administrators than the +r was. The bridge manager at Element suggested creating a cloak on IRC for IP addresses starting with 2001:470:1af1:104::, which would at least allow admins not to have to memorize that.
Also, is it possible to define command aliases so IRC administrators can simply type /lockforspam instead of the whole MODE command?