In T331058#8736869, @Niharika wrote:

@Tchanders and I discussed this today. My preference would be for us to disallow muting temporary users from Special:Mute and Special:Preferences.

What's the reasoning for this preference? I don't have a strong preference, but it seems like when in doubt we should default to treating temp accounts in the same way IP editor accounts were treated previously, right? And it seems like completing this task could limit the possibility of temp accounts being used for harassment.

In general I think it makes sense to complete this task, but I want to be sure I'm not missing something. I'm moving this task to Blocked until we hear back from @Niharika.

Noting on this task that the related discussion is happening on T331058: Make Special:Mute only usable for named users

As far as I can tell, this functionality already exists. I am able to mute a temp user in my Echo notification preferences.

In T344647#9333582, @kostajh wrote:

As far as I can tell, this functionality already exists. I am able to mute a temp user in my Echo notification preferences.

This is correct.

What was done

We did some work to disable Special:Mute muting temporary users, but the work to do the same for Echo preferences was never done.

The work we did on Special:Mute was (from T331058):

• Only named users should be able to access Special:Mute. Anons and temporary users should see an error.
• Special:Mute/<username> should display an error if <username> is not a named user's name (e.g. if it is an IP, temp user, nonexistent user, or empty)
• Named users should see a "Mute preferences" link in their side menu on pages that have a 'relevant user' (e.g. Special:Contributions/<someuser>, Special:Block/<someuser>, etc) - but only if <someuser> is a named user. Temp and anon users should not see this link.

What we should do now

We can leave Echo as-is.

We should undo the following:

• Special:Mute/<username> should display an error if <username> is not a named user's name (e.g. if it is an IP, temp user, nonexistent user, or empty)
• Named users should see a "Mute preferences" link in their side menu on pages that have a 'relevant user' (e.g. Special:Contributions/<someuser>, Special:Block/<someuser>, etc) - but only if <someuser> is a named user. Temp and anon users should not see this link.

Change 974519 had a related patch set uploaded (by Tchanders; author: Tchanders):

[mediawiki/core@master] Re-enable muting temporary users

https://gerrit.wikimedia.org/r/974519

See also T351091 about being able to mute all non-perm users

Change 974519 merged by jenkins-bot:

[mediawiki/core@master] Re-enable muting temporary users

https://gerrit.wikimedia.org/r/974519

I tested muting and unmuting temporary and named users on beta enwiki and beta dewiki. I did so via Special:Mute and Special:Preferences.

I checked that after muting a temporary user it does actually stop sending notifications when the temp user mentions my username.

Two things to note are:

• Special:Mute for a temp user does not include Mute emails from this user (which makes sense as temp users don't have emails) but you can still add a temp username to Prohibit these users from emailing me: on Special:Preferences.
• On wikis without temporary usernames enabled (e.g. enwiki beta), Special:Mute for a temporary username does include Mute emails from this user, I guess because the username is considered a named user.

Test environments: https://en.wikipedia.beta.wmflabs.org and https://de.wikipedia.beta.wmflabs.org MediaWiki 1.42.0-alpha (ef0e9e0) 09:49, 14 December 2023.

Special:Mute for a temp user does not include Mute emails from this user (which makes sense as temp users don't have emails) but you can still add a temp username to Prohibit these users from emailing me: on Special:Preferences.

Thanks, filed as T353561 - dependent on T332030.