sendConfirmAndMigrateMail has two purposes with its [[Special:MergeAccount]] link: confirming the email and merging unattached accounts; however, if a account has a confirmed email, it's skipped:
if ( $user->isEmailConfirmed() ) { $this->output( "ERROR: The user '$username@$wgDBname' already has a confirmed email address\n" ); return; }
I think it's conceivable that we or someone may want to solicit those global users too to merge the unattached accounts belonging to them.
In Wikimedia projects' case, if I understand the data correctly, they are the global users corresponding to a subset of those 114,604 non-attached accounts "who clash with a global account" as of 2013-05-06.
https://www.mediawiki.org/wiki/Admin_tools_development/SUL_Audit#Metrics
According to [[mw:Admin tools development/SUL Audit/Metrics 20130417]] about 80 % of the unattached accounts have an email set; no idea how many global accounts do nor how many of those are already emailconfirmed, but it's probably a good proportion.
Version: master
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=71241