diff --git a/Documentation/SOGoInstallationGuide.asciidoc b/Documentation/SOGoInstallationGuide.asciidoc
index 475d19017..f209764e5 100644
--- a/Documentation/SOGoInstallationGuide.asciidoc
+++ b/Documentation/SOGoInstallationGuide.asciidoc
@@ -2118,6 +2118,15 @@ automatically forwarding mails. When set to `0` (default), no constraint
 is enforced. When set to `1`, only internal domains can be used. When
 set to `2`, only external domains can be used.
 
+|D |SOGoForwardConstraintsDomains
+|Parameter used to set which domains are allowed as external domains
+when SOGoForwardConstraints is set to `2`. For example, setting:
+
+SOGoForwardConstraintsDomains = ("gmail.com", "googlemail.com");
+
+will allow users to forward emails to only `gmail.com` and `googlemail.com` domains.
+When empty or undefined, no constraints are imposed.
+
 |D |SOGoSieveScriptsEnabled
 |Parameter used to activate the edition from the preferences windows of
 server-side mail filters. Requires Sieve script support on the IMAP
diff --git a/NEWS b/NEWS
index ab4505a0a..a2ea31925 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,7 @@
 
 New features
  - [core] Debian 10 (Buster) support for x86_64 (#4775)
+ - [core] now possible to specify which domains you can forward your mails to
 
 Enhancements
  - [web] avoid saving an empty calendar name
diff --git a/SoObjects/SOGo/SOGoDomainDefaults.h b/SoObjects/SOGo/SOGoDomainDefaults.h
index d64130dfa..3d7d61139 100644
--- a/SoObjects/SOGo/SOGoDomainDefaults.h
+++ b/SoObjects/SOGo/SOGoDomainDefaults.h
@@ -1,6 +1,6 @@
 /* SOGoDomainDefaults.h - this file is part of SOGo
  *
- * Copyright (C) 2009-2016 Inverse inc.
+ * Copyright (C) 2009-2019 Inverse inc.
  *
  * This file is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -51,6 +51,7 @@
 - (BOOL) sieveScriptsEnabled;
 - (BOOL) forwardEnabled;
 - (int) forwardConstraints;
+- (NSArray *) forwardConstraintsDomains;
 - (BOOL) vacationEnabled;
 - (NSString *) vacationDefaultSubject;
 - (NSString *) vacationHeaderTemplateFile;
diff --git a/SoObjects/SOGo/SOGoDomainDefaults.m b/SoObjects/SOGo/SOGoDomainDefaults.m
index 6f49d0b81..0051dfba3 100644
--- a/SoObjects/SOGo/SOGoDomainDefaults.m
+++ b/SoObjects/SOGo/SOGoDomainDefaults.m
@@ -1,6 +1,6 @@
 /* SOGoDomainDefaults.m - this file is part of SOGo
  *
- * Copyright (C) 2009-2016 Inverse inc.
+ * Copyright (C) 2009-2019 Inverse inc.
  *
  * This file is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -215,6 +215,11 @@
   return (v > 2 ? 0 : v);
 }
 
+- (NSArray *) forwardConstraintsDomains
+{
+  return [self stringArrayForKey: @"SOGoForwardConstraintsDomains"];
+}
+
 - (BOOL) vacationEnabled
 {
   return [self boolForKey: @"SOGoVacationEnabled"];
diff --git a/UI/PreferencesUI/English.lproj/Localizable.strings b/UI/PreferencesUI/English.lproj/Localizable.strings
index 56019e7dd..464db0b46 100644
--- a/UI/PreferencesUI/English.lproj/Localizable.strings
+++ b/UI/PreferencesUI/English.lproj/Localizable.strings
@@ -63,6 +63,7 @@
 = "Please specify an address to which you want to forward your messages.";
 "You are not allowed to forward your messages to an external email address." = "You are not allowed to forward your messages to an external email address.";
 "You are not allowed to forward your messages to an internal email address." = "You are not allowed to forward your messages to an internal email address.";
+"You are not allowed to forward your messages to this domain:" = "You are not allowed to forward your messages to this domain:";
 
 /* d & t */
 "Current Time Zone" = "Current Time Zone";
diff --git a/UI/PreferencesUI/UIxPreferences.m b/UI/PreferencesUI/UIxPreferences.m
index 0994c0a90..6a79469a3 100644
--- a/UI/PreferencesUI/UIxPreferences.m
+++ b/UI/PreferencesUI/UIxPreferences.m
@@ -1,6 +1,6 @@
 /* UIxPreferences.m - this file is part of SOGo
  *
- * Copyright (C) 2007-2018 Inverse inc.
+ * Copyright (C) 2007-2019 Inverse inc.
  *
  * This file is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -1495,6 +1495,18 @@ static NSArray *reminderValues = nil;
   return [NSString stringWithFormat: @"%d", [dd forwardConstraints]];
 }
 
+- (NSString *) forwardConstraintsDomains
+{
+  NSMutableArray *domains;
+  SOGoDomainDefaults *dd;
+
+  dd = [[context activeUser] domainDefaults];
+  domains = [NSMutableArray array];
+  [domains addObjectsFromArray: [dd forwardConstraintsDomains]];
+
+  return [domains jsonRepresentation];
+}
+
 //
 // Used by templates
 //
diff --git a/UI/Templates/PreferencesUI/UIxPreferences.wox b/UI/Templates/PreferencesUI/UIxPreferences.wox
index db4e53927..eb7d74e2c 100644
--- a/UI/Templates/PreferencesUI/UIxPreferences.wox
+++ b/UI/Templates/PreferencesUI/UIxPreferences.wox
@@ -21,6 +21,7 @@
     var defaultEmailAddresses = '<var:string value="defaultEmailAddresses" const:escapeHTML="NO"/>';
     var defaultCalendarCategories = <var:string value="defaultCalendarCategoriesColors" const:escapeHTML="NO"/>;
     var forwardConstraints = <var:string value="forwardConstraints" const:escapeHTML="NO"/>;
+    var forwardConstraintsDomains = <var:string value="forwardConstraintsDomains" const:escapeHTML="NO"/>;
     var sieveCapabilities = <var:string value="sieveCapabilities" const:escapeHTML="NO"/>;
   </script>
 
diff --git a/UI/WebServerResources/js/Preferences/PreferencesController.js b/UI/WebServerResources/js/Preferences/PreferencesController.js
index 135075b00..73bd081b1 100644
--- a/UI/WebServerResources/js/Preferences/PreferencesController.js
+++ b/UI/WebServerResources/js/Preferences/PreferencesController.js
@@ -347,6 +347,12 @@
             Dialog.alert(l('Error'), l("You are not allowed to forward your messages to an internal email address."));
             sendForm = false;
           }
+          else if ($window.forwardConstraints == 2 &&
+                   $window.forwardConstraintsDomains.length > 0 &&
+                   $window.forwardConstraintsDomains.indexOf(domain) < 0) {
+            Dialog.alert(l('Error'), l("You are not allowed to forward your messages to this domain:") + " " + domain);
+            sendForm = false;
+          }
         }
       }