diff --git a/build/integration/sharees_features/sharees.feature b/build/integration/sharees_features/sharees.feature
index 0e52c89f778..b2a88701988 100644
--- a/build/integration/sharees_features/sharees.feature
+++ b/build/integration/sharees_features/sharees.feature
@@ -9,6 +9,13 @@ Feature: sharees
     And group "ShareeGroup" exists
     And user "test" belongs to group "ShareeGroup"
     And user "Sharee2" exists
+    And As an "admin"
+    And sending "PUT" to "/cloud/users/Sharee2" with
+      | key   | email |
+      | value | sharee2@system.com |
+    And sending "PUT" to "/cloud/users/Sharee2" with
+      | key   | additional_mail |
+      | value | sharee2@secondary.com |
 
   Scenario: Search without exact match
     Given As an "test"
@@ -20,7 +27,7 @@ Feature: sharees
     And "exact users" sharees returned is empty
     And "users" sharees returned are
       | Sharee1 | 0 | Sharee1 | Sharee1 |
-      | Sharee2 | 0 | Sharee2 | Sharee2 |
+      | Sharee2 | 0 | Sharee2 | sharee2@system.com |
     And "exact groups" sharees returned is empty
     And "groups" sharees returned are
       | ShareeGroup | 1 | ShareeGroup |
@@ -37,7 +44,7 @@ Feature: sharees
     And "exact users" sharees returned is empty
     And "users" sharees returned are
       | Sharee1 | 0 | Sharee1 | Sharee1 |
-      | Sharee2 | 0 | Sharee2 | Sharee2 |
+      | Sharee2 | 0 | Sharee2 | sharee2@system.com |
     And "exact groups" sharees returned is empty
     And "groups" sharees returned are
       | ShareeGroup | 1 | ShareeGroup |
@@ -258,8 +265,183 @@ Feature: sharees
     And "exact users" sharees returned is empty
     And "users" sharees returned are
       | Sharee1 | 0 | Sharee1 | Sharee1 |
-      | Sharee2 | 0 | Sharee2 | Sharee2 |
+      | Sharee2 | 0 | Sharee2 | sharee2@system.com |
     And "exact groups" sharees returned is empty
     And "groups" sharees returned is empty
     And "exact remotes" sharees returned is empty
     And "remotes" sharees returned is empty
+
+  Scenario: Search user by system e-mail address
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@system.com |
+      | itemType  | file |
+      | shareType | 0 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    # UserPlugin provides two identical results (except for the field order, but
+    # that is hidden by the check).
+    And "exact users" sharees returned are
+      | Sharee2 | 0 | Sharee2 | sharee2@system.com |
+      | Sharee2 | 0 | Sharee2 | sharee2@system.com |
+    And "users" sharees returned is empty
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned is empty
+    And "emails" sharees returned is empty
+
+  Scenario: Search user by system e-mail address without exact match
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@system.c |
+      | itemType  | file |
+      | shareType | 0 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned is empty
+    And "users" sharees returned are
+      | Sharee2 | 0 | Sharee2 | sharee2@system.com |
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned is empty
+    And "emails" sharees returned is empty
+
+  Scenario: Search user by secondary e-mail address
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@secondary.com |
+      | itemType  | file |
+      | shareType | 0 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    # UserPlugin only searches in the system e-mail address, but not in
+    # secondary addresses.
+    And "exact users" sharees returned is empty
+    And "users" sharees returned is empty
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned is empty
+    And "emails" sharees returned is empty
+
+  Scenario: Search user by secondary e-mail address without exact match
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@secondary.c |
+      | itemType  | file |
+      | shareType | 0 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned is empty
+    # UserPlugin only searches in the system e-mail address, but not in
+    # secondary addresses.
+    And "users" sharees returned is empty
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned is empty
+    And "emails" sharees returned is empty
+
+  Scenario: Search e-mail
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@unknown.com |
+      | itemType  | file |
+      | shareType | 4 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned is empty
+    And "users" sharees returned is empty
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned are
+      | sharee2@unknown.com | 4 | sharee2@unknown.com |
+    And "emails" sharees returned is empty
+
+  Scenario: Search e-mail matching system e-mail address of user
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@system.com |
+      | itemType  | file |
+      | shareType | 4 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned are
+      | Sharee2 (sharee2@system.com) | 0 | Sharee2 | sharee2@system.com |
+    And "users" sharees returned is empty
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned is empty
+    And "emails" sharees returned is empty
+
+  Scenario: Search e-mail partially matching system e-mail address of user
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@system.c |
+      | itemType  | file |
+      | shareType | 4 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned is empty
+    # MailPlugin adds a result for every e-mail address of the contact unless
+    # there is an exact match.
+    And "users" sharees returned are
+      | Sharee2 (sharee2@system.com)    | 0 | Sharee2 | sharee2@system.com |
+      | Sharee2 (sharee2@secondary.com) | 0 | Sharee2 | sharee2@secondary.com |
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned are
+      | sharee2@system.c | 4 | sharee2@system.c |
+    And "emails" sharees returned is empty
+
+  Scenario: Search e-mail matching secondary e-mail address of user
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@secondary.com |
+      | itemType  | file |
+      | shareType | 4 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned are
+      | Sharee2 (sharee2@secondary.com) | 0 | Sharee2 | sharee2@secondary.com |
+    And "users" sharees returned is empty
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned is empty
+    And "emails" sharees returned is empty
+
+  Scenario: Search e-mail partially matching secondary e-mail address of user
+    Given As an "test"
+    When getting sharees for
+      | search    | sharee2@secondary.c |
+      | itemType  | file |
+      | shareType | 4 |
+    Then the OCS status code should be "100"
+    And the HTTP status code should be "200"
+    And "exact users" sharees returned is empty
+    # MailPlugin adds a result for every e-mail address of the contact unless
+    # there is an exact match.
+    And "users" sharees returned are
+      | Sharee2 (sharee2@system.com)    | 0 | Sharee2 | sharee2@system.com |
+      | Sharee2 (sharee2@secondary.com) | 0 | Sharee2 | sharee2@secondary.com |
+    And "exact groups" sharees returned is empty
+    And "groups" sharees returned is empty
+    And "exact remotes" sharees returned is empty
+    And "remotes" sharees returned is empty
+    And "exact emails" sharees returned are
+      | sharee2@secondary.c | 4 | sharee2@secondary.c |
+    And "emails" sharees returned is empty