Last modified: 2010-05-15 15:33:08 UTC
Some sites may simply not have a working e-mail server available, others may consider it a security risk (potential spam issues etc). User-to-user email in particular may be something that you don't always want available, so it might be useful to be able to disable that separately from e-mail password reminders.
Checked in $wgEnableEmail and $wgEnableUserEmail settings.