/usr/share/gosa/plugins/admin/ is in gosa-plugin-mail 2.7.4+reloaded2-9ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gosa/plugins/admin/groups/
/usr/share/gosa/plugins/admin/groups/mail/
/usr/share/gosa/plugins/admin/groups/mail/class_groupMail.inc
/usr/share/gosa/plugins/admin/groups/mail/mail.tpl
/usr/share/gosa/plugins/admin/groups/mail/paste_mail.tpl
/usr/share/gosa/plugins/admin/ogroups/
/usr/share/gosa/plugins/admin/ogroups/mail/
/usr/share/gosa/plugins/admin/ogroups/mail/class_mailogroup.inc
/usr/share/gosa/plugins/admin/ogroups/mail/mail.tpl
/usr/share/gosa/plugins/admin/ogroups/mail/paste_mail.tpl
/usr/share/gosa/plugins/admin/systems/
/usr/share/gosa/plugins/admin/systems/services/
/usr/share/gosa/plugins/admin/systems/services/imap/
/usr/share/gosa/plugins/admin/systems/services/imap/class_goImapServer.inc
/usr/share/gosa/plugins/admin/systems/services/imap/goImapServer.tpl
/usr/share/gosa/plugins/admin/systems/services/mail/
/usr/share/gosa/plugins/admin/systems/services/mail/class_goMailServer.inc
/usr/share/gosa/plugins/admin/systems/services/mail/goMailServer.tpl
/usr/share/gosa/plugins/admin/systems/services/spam/
/usr/share/gosa/plugins/admin/systems/services/spam/class_goSpamServer.inc
/usr/share/gosa/plugins/admin/systems/services/spam/class_goSpamServerRule.inc
/usr/share/gosa/plugins/admin/systems/services/spam/goSpamServer.tpl
/usr/share/gosa/plugins/admin/systems/services/spam/goSpamServerRule.tpl
/usr/share/gosa/plugins/admin/systems/services/virus/
/usr/share/gosa/plugins/admin/systems/services/virus/class_goVirusServer.inc
/usr/share/gosa/plugins/admin/systems/services/virus/goVirusServer.tpl