diff --git a/application/Espo/Core/Utils/Auth.php b/application/Espo/Core/Utils/Auth.php
index 0b8ed56487..736dc7320a 100644
--- a/application/Espo/Core/Utils/Auth.php
+++ b/application/Espo/Core/Utils/Auth.php
@@ -168,7 +168,7 @@ class Auth
             return;
         }
 
-        $user = $this->authentication->login($username, $password, $authToken);
+        $user = $this->authentication->login($username, $password, $authToken, $this->isPortal());
 
         $authLogRecord = null;
 
diff --git a/application/Espo/Core/Utils/Authentication/Espo.php b/application/Espo/Core/Utils/Authentication/Espo.php
index e0bb97ab3b..0ea680dc2a 100644
--- a/application/Espo/Core/Utils/Authentication/Espo.php
+++ b/application/Espo/Core/Utils/Authentication/Espo.php
@@ -33,7 +33,7 @@ use \Espo\Core\Exceptions\Error;
 
 class Espo extends Base
 {
-    public function login($username, $password, \Espo\Entities\AuthToken $authToken = null)
+    public function login($username, $password, \Espo\Entities\AuthToken $authToken = null, $isPortal = null)
     {
         if ($authToken) {
             $hash = $authToken->get('hash');
@@ -51,4 +51,3 @@ class Espo extends Base
         return $user;
     }
 }
-
diff --git a/application/Espo/Core/Utils/Authentication/LDAP.php b/application/Espo/Core/Utils/Authentication/LDAP.php
index 82594e2fc1..1a8333941f 100644
--- a/application/Espo/Core/Utils/Authentication/LDAP.php
+++ b/application/Espo/Core/Utils/Authentication/LDAP.php
@@ -34,7 +34,7 @@ use Espo\Core\Utils\Config;
 use Espo\Core\ORM\EntityManager;
 use Espo\Core\Utils\Auth;
 
-class LDAP extends Base
+class LDAP extends Espo
 {
     private $utils;
 
@@ -100,12 +100,19 @@ class LDAP extends Base
      *
      * @return \Espo\Entities\User | null
      */
-    public function login($username, $password, \Espo\Entities\AuthToken $authToken = null)
+    public function login($username, $password, \Espo\Entities\AuthToken $authToken = null, $isPortal = null)
     {
         if ($authToken) {
             return $this->loginByToken($username, $authToken);
         }
 
+        if ($isPortal) {
+            $useLdapAuthForPortalUser = $this->getUtils()->getOption('portalUserLdapAuth');
+            if (!$useLdapAuthForPortalUser) {
+                return parent::login($username, $password, $authToken, $isPortal);
+            }
+        }
+
         $ldapClient = $this->getLdapClient();
 
         /* Login LDAP system user (ldapUsername, ldapPassword) */
@@ -184,7 +191,7 @@ class LDAP extends Base
         $user = $this->getEntityManager()->getEntity('User', $userId);
 
         $tokenUsername = $user->get('userName');
-        if ($username != $tokenUsername) {
+        if (strtolower($username) != strtolower($tokenUsername)) {
             $GLOBALS['log']->alert('Unauthorized access attempt for user ['.$username.'] from IP ['.$_SERVER['REMOTE_ADDR'].']');
             return null;
         }
@@ -328,4 +335,4 @@ class LDAP extends Base
 
         return $fields;
     }
-}
\ No newline at end of file
+}
diff --git a/application/Espo/Core/Utils/Authentication/LDAP/Utils.php b/application/Espo/Core/Utils/Authentication/LDAP/Utils.php
index 99cf33424a..8c21b7903f 100644
--- a/application/Espo/Core/Utils/Authentication/LDAP/Utils.php
+++ b/application/Espo/Core/Utils/Authentication/LDAP/Utils.php
@@ -67,6 +67,7 @@ class Utils
         'userTeamsIds' => 'ldapUserTeamsIds',
         'userDefaultTeamId' => 'ldapUserDefaultTeamId',
         'userObjectClass' => 'ldapUserObjectClass',
+        'portalUserLdapAuth' => 'ldapPortalUserLdapAuth',
     );
 
     /**
@@ -86,6 +87,7 @@ class Utils
         'userLoginFilter',
         'userTeamsIds',
         'userDefaultTeamId',
+        'portalUserLdapAuth',
     );
 
     /**
@@ -163,7 +165,7 @@ class Utils
      */
     public function getOption($name, $returns = null)
     {
-        if (isset($this->options)) {
+        if (!isset($this->options)) {
             $this->getOptions();
         }
 
@@ -187,4 +189,4 @@ class Utils
         return $zendOptions;
     }
 
-}
\ No newline at end of file
+}
diff --git a/application/Espo/Core/defaults/systemConfig.php b/application/Espo/Core/defaults/systemConfig.php
index 78c012619d..00b6d2195e 100644
--- a/application/Espo/Core/defaults/systemConfig.php
+++ b/application/Espo/Core/defaults/systemConfig.php
@@ -134,6 +134,7 @@ return array (
         'ldapAccountFilterFormat',
         'ldapTryUsernameSplit',
         'ldapOptReferrals',
+        'ldapPortalUserLdapAuth',
         'ldapCreateEspoUser',
         'ldapAccountDomainName',
         'ldapAccountDomainNameShort',
@@ -206,5 +207,5 @@ return array (
     ],
     'requiredMysqlVersion' => '5.5.3',
     'recommendedMysqlParams' => [],
-
+    'ldapPortalUserLdapAuth' => false,
 );
diff --git a/application/Espo/Resources/i18n/en_US/Settings.json b/application/Espo/Resources/i18n/en_US/Settings.json
index b9b95a2935..4f7b8cd9e1 100644
--- a/application/Espo/Resources/i18n/en_US/Settings.json
+++ b/application/Espo/Resources/i18n/en_US/Settings.json
@@ -40,6 +40,7 @@
         "ldapAccountCanonicalForm": "Account Canonical Form",
         "ldapAccountDomainName": "Account Domain Name",
         "ldapTryUsernameSplit": "Try Username Split",
+        "ldapPortalUserLdapAuth": "Use LDAP Authentication for Portal Users",
         "ldapCreateEspoUser": "Create User in EspoCRM",
         "ldapSecurity": "Security",
         "ldapUserLoginFilter": "User Login Filter",
@@ -137,6 +138,7 @@
         "ldapBaseDn": "The default base DN used for searching users. E.g. \"OU=users,OU=espocrm,DC=test, DC=lan\".",
         "ldapTryUsernameSplit": "The option to split a username with the domain.",
         "ldapOptReferrals": "if referrals should be followed to the LDAP client.",
+        "ldapPortalUserLdapAuth": "Allow portal users to use LDAP authentication instead of Espo authentication.",
         "ldapCreateEspoUser": "This option allows EspoCRM to create a user from the LDAP.",
         "ldapUserFirstNameAttribute": "LDAP attribute which is used to determine the user first name. E.g. \"givenname\".",
         "ldapUserLastNameAttribute": "LDAP attribute which is used to determine the user last name. E.g. \"sn\".",
diff --git a/application/Espo/Resources/layouts/Settings/authentication.json b/application/Espo/Resources/layouts/Settings/authentication.json
index 138652784a..576ac3ddac 100644
--- a/application/Espo/Resources/layouts/Settings/authentication.json
+++ b/application/Espo/Resources/layouts/Settings/authentication.json
@@ -20,6 +20,7 @@
             [{"name": "ldapUserLoginFilter", "fullWidth": true}],
             [{"name": "ldapAccountDomainName"}, {"name": "ldapAccountDomainNameShort"}],
             [{"name": "ldapTryUsernameSplit"}, {"name": "ldapOptReferrals"}],
+            [{"name": "ldapPortalUserLdapAuth"}, false],
             [{"name": "ldapCreateEspoUser"}, false],
             [{"name": "ldapUserFirstNameAttribute"}, {"name": "ldapUserLastNameAttribute"}],
             [{"name": "ldapUserTitleAttribute"}, false],
diff --git a/application/Espo/Resources/metadata/entityDefs/Settings.json b/application/Espo/Resources/metadata/entityDefs/Settings.json
index 3f12a7b5d4..02a787f5fe 100644
--- a/application/Espo/Resources/metadata/entityDefs/Settings.json
+++ b/application/Espo/Resources/metadata/entityDefs/Settings.json
@@ -209,6 +209,11 @@
             "type": "bool",
             "tooltip": true
         },
+        "ldapPortalUserLdapAuth": {
+            "type": "bool",
+            "default": false,
+            "tooltip": true
+        },
         "ldapCreateEspoUser": {
             "type": "bool",
             "default": true,
diff --git a/application/Espo/Services/EmailAddress.php b/application/Espo/Services/EmailAddress.php
index 2d2853af40..0c36e2dc2d 100644
--- a/application/Espo/Services/EmailAddress.php
+++ b/application/Espo/Services/EmailAddress.php
@@ -35,6 +35,7 @@ use \Espo\Core\Exceptions\Error;
 
 class EmailAddress extends Record
 {
+    const ERASED_PREFIX = 'ERASED:';
 
     protected function findInAddressBookByEntityType($query, $limit, $entityType, &$result)
     {
@@ -67,24 +68,31 @@ class EmailAddress extends Record
         foreach ($collection as $entity) {
             $emailAddress = $entity->get('emailAddress');
 
-            $result[] = array(
+            if ($emailAddress) {
+                if (strpos($emailAddress, self::ERASED_PREFIX) === 0) {
+                    continue;
+                }
+            }
+
+            $result[] = [
                 'emailAddress' => $emailAddress,
                 'entityName' => $entity->get('name'),
                 'entityType' => $entityType,
                 'entityId' => $entity->id
-            );
+            ];
 
             $emailAddressData = $this->getEntityManager()->getRepository('EmailAddress')->getEmailAddressData($entity);
             foreach ($emailAddressData as $d) {
                 if ($emailAddress != $d->emailAddress) {
                     $emailAddress = $d->emailAddress;
-                    $result[] = array(
-                        'emailAddress' => $emailAddress,
-                        'entityName' => $entity->get('name'),
-                        'entityType' => $entityType,
-                        'entityId' => $entity->id
-                    );
-                    break;
+                    if (strpos($emailAddress, $query) === 0 && strpos($emailAddress, self::ERASED_PREFIX) !== 0) {
+                        $result[] = [
+                            'emailAddress' => $emailAddress,
+                            'entityName' => $entity->get('name'),
+                            'entityType' => $entityType,
+                            'entityId' => $entity->id
+                        ];
+                    }
                 }
             }
         }
@@ -125,24 +133,31 @@ class EmailAddress extends Record
         foreach ($collection as $entity) {
             $emailAddress = $entity->get('emailAddress');
 
-            $result[] = array(
+            if ($emailAddress) {
+                if (strpos($emailAddress, self::ERASED_PREFIX) === 0) {
+                    continue;
+                }
+            }
+
+            $result[] = [
                 'emailAddress' => $emailAddress,
                 'entityName' => $entity->get('name'),
                 'entityType' => 'User',
                 'entityId' => $entity->id
-            );
+            ];
 
             $emailAddressData = $this->getEntityManager()->getRepository('EmailAddress')->getEmailAddressData($entity);
             foreach ($emailAddressData as $d) {
                 if ($emailAddress != $d->emailAddress) {
                     $emailAddress = $d->emailAddress;
-                    $result[] = array(
-                        'emailAddress' => $emailAddress,
-                        'entityName' => $entity->get('name'),
-                        'entityType' => 'User',
-                        'entityId' => $entity->id
-                    );
-                    break;
+                    if (strpos($emailAddress, $query) === 0 && strpos($emailAddress, self::ERASED_PREFIX) !== 0) {
+                        $result[] = [
+                            'emailAddress' => $emailAddress,
+                            'entityName' => $entity->get('name'),
+                            'entityType' => 'User',
+                            'entityId' => $entity->id
+                        ];
+                    }
                 }
             }
         }