diff --git a/enzevalos_iphone.xcodeproj/project.pbxproj b/enzevalos_iphone.xcodeproj/project.pbxproj
index 8e0d407d344792489a23016dccc6e02753d2defe..e6905e90923eec20143baf91e040ce12ec76ab3f 100644
--- a/enzevalos_iphone.xcodeproj/project.pbxproj
+++ b/enzevalos_iphone.xcodeproj/project.pbxproj
@@ -96,6 +96,7 @@
 		479C649A21F45DAF00A01071 /* HideShowPasswordTextField.swift in Sources */ = {isa = PBXBuildFile; fileRef = 479C649821F45DAF00A01071 /* HideShowPasswordTextField.swift */; };
 		479C649B21F45DAF00A01071 /* PasswordToggleVisibilityView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 479C649921F45DAF00A01071 /* PasswordToggleVisibilityView.swift */; };
 		47A2A56E2350A4EF0013883D /* MoreInformationViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47A2A56D2350A4EF0013883D /* MoreInformationViewController.swift */; };
+		47A2A57223599D180013883D /* FeedbackButtonHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47A2A57123599D180013883D /* FeedbackButtonHelper.swift */; };
 		47A5D6E22294BF3B0084F81D /* TempKey.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47A5D6E12294BF3A0084F81D /* TempKey.swift */; };
 		47A5D6E42294BFF50084F81D /* Logger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47A5D6E32294BFF50084F81D /* Logger.swift */; };
 		47C036FF2347C0F5006295E8 /* ImportKeyOverviewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47C036FE2347C0F4006295E8 /* ImportKeyOverviewController.swift */; };
@@ -349,6 +350,7 @@
 		479C649821F45DAF00A01071 /* HideShowPasswordTextField.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = HideShowPasswordTextField.swift; sourceTree = "<group>"; };
 		479C649921F45DAF00A01071 /* PasswordToggleVisibilityView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PasswordToggleVisibilityView.swift; sourceTree = "<group>"; };
 		47A2A56D2350A4EF0013883D /* MoreInformationViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MoreInformationViewController.swift; sourceTree = "<group>"; };
+		47A2A57123599D180013883D /* FeedbackButtonHelper.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedbackButtonHelper.swift; sourceTree = "<group>"; };
 		47A5D6D52294B4830084F81D /* GTMAppAuth.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = GTMAppAuth.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		47A5D6DB2294B5220084F81D /* libz.1.1.3.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libz.1.1.3.tbd; path = usr/lib/libz.1.1.3.tbd; sourceTree = SDKROOT; };
 		47A5D6DD2294B5480084F81D /* AppAuth.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = AppAuth.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -969,6 +971,7 @@
 				A17FDFF2202C685800F7BA89 /* StudySettings.swift */,
 				47D1302A1F7CEE6D007B14DF /* DebugSettings.swift */,
 				A111F6AB1FA77AF80060AFDE /* Logging */,
+				47A2A57123599D180013883D /* FeedbackButtonHelper.swift */,
 			);
 			name = "debug and study";
 			sourceTree = "<group>";
@@ -1576,6 +1579,7 @@
 				F18B44621E73286C0080C041 /* ReadVENDelegate.swift in Sources */,
 				475B00421F7BB6D6006CDD41 /* PersistentKey+CoreDataClass.swift in Sources */,
 				A10DAA5721F37600005D8BBB /* IntroInfoButton.swift in Sources */,
+				47A2A57223599D180013883D /* FeedbackButtonHelper.swift in Sources */,
 				3EC35F2420037651008BDF95 /* InvitationHelper.swift in Sources */,
 				A1B49E6421E55ECD00ED86FC /* IntroPageViewController.swift in Sources */,
 				A1D5076F1E80257A00B68B38 /* KeyViewController.swift in Sources */,
diff --git a/enzevalos_iphone/Base.lproj/Main.storyboard b/enzevalos_iphone/Base.lproj/Main.storyboard
index 04981b1796c4e8dd0055598d75e45add354f57f3..39c78cdb74814713876fb78d5820b7ef8819c150 100644
--- a/enzevalos_iphone/Base.lproj/Main.storyboard
+++ b/enzevalos_iphone/Base.lproj/Main.storyboard
@@ -16,7 +16,7 @@
             <objects>
                 <tableViewController storyboardIdentifier="UITableViewController-Ouw-WD-EV6" id="Ouw-WD-EV6" customClass="ReadViewController" customModule="enzevalos_iphone" customModuleProvider="target" sceneMemberID="viewController">
                     <tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="static" style="grouped" separatorStyle="default" allowsSelection="NO" rowHeight="44" sectionHeaderHeight="8" sectionFooterHeight="1" id="oZT-OA-Re5">
-                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="808"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <color key="backgroundColor" red="0.93725490199999995" green="0.93725490199999995" blue="0.95686274510000002" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                         <sections>
@@ -825,7 +825,7 @@
             <objects>
                 <tableViewController storyboardIdentifier="UITableViewController-ooe-0X-glz" id="ooe-0X-glz" customClass="ListViewController" customModule="enzevalos_iphone" customModuleProvider="target" sceneMemberID="viewController">
                     <tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="prototypes" style="plain" separatorStyle="default" rowHeight="44" sectionHeaderHeight="28" sectionFooterHeight="28" id="ipK-4X-lVA">
-                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="808"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
                         <prototypes>
@@ -911,7 +911,7 @@
             <objects>
                 <tableViewController storyboardIdentifier="UITableViewController-8Di-x2-cWQ" useStoryboardIdentifierAsRestorationIdentifier="YES" id="8Di-x2-cWQ" customClass="ContactViewController" customModule="enzevalos_iphone" customModuleProvider="target" sceneMemberID="viewController">
                     <tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="prototypes" style="grouped" separatorStyle="default" rowHeight="44" sectionHeaderHeight="18" sectionFooterHeight="18" id="lK7-ug-OyQ">
-                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="808"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <color key="backgroundColor" cocoaTouchSystemColor="groupTableViewBackgroundColor"/>
                         <prototypes>
@@ -1287,7 +1287,7 @@
                                 <rect key="frame" x="0.0" y="809.33333333333337" width="414" height="44"/>
                                 <autoresizingMask key="autoresizingMask"/>
                                 <tableViewCellContentView key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" tableViewCell="hTc-vs-AIl" id="pJ9-4e-7at">
-                                    <rect key="frame" x="0.0" y="0.0" width="376" height="43.666666666666664"/>
+                                    <rect key="frame" x="0.0" y="0.0" width="388" height="43.666666666666664"/>
                                     <autoresizingMask key="autoresizingMask"/>
                                     <subviews>
                                         <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" translatesAutoresizingMaskIntoConstraints="NO" id="Ll6-yF-xkq">
@@ -1356,7 +1356,7 @@
             <objects>
                 <viewController id="jYD-fk-aIP" customClass="KeyViewController" customModule="enzevalos_iphone" customModuleProvider="target" sceneMemberID="viewController">
                     <tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="prototypes" style="grouped" separatorStyle="default" rowHeight="44" sectionHeaderHeight="18" sectionFooterHeight="18" id="ZAH-bZ-S6n">
-                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="808"/>
                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES"/>
                         <color key="backgroundColor" cocoaTouchSystemColor="groupTableViewBackgroundColor"/>
                         <edgeInsets key="layoutMargins" top="10" left="20" bottom="10" right="20"/>
@@ -1539,7 +1539,7 @@
             <objects>
                 <tableViewController storyboardIdentifier="exportInfoViewController" id="7Pd-d5-0wz" customClass="ExportInfoViewController" customModule="enzevalos_iphone" customModuleProvider="target" sceneMemberID="viewController">
                     <tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" showsHorizontalScrollIndicator="NO" dataMode="prototypes" style="grouped" separatorStyle="default" sectionIndexMinimumDisplayRowCount="1" rowHeight="-1" sectionHeaderHeight="18" sectionFooterHeight="18" id="2Uv-bd-pB1">
-                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="808"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <color key="backgroundColor" cocoaTouchSystemColor="groupTableViewBackgroundColor"/>
                         <prototypes>
@@ -2027,7 +2027,7 @@ Um deine sicheren E-Mails auch auf einem anderen Gerät lesen zu können, muss d
                             </connections>
                         </barButtonItem>
                         <button key="titleView" opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" id="iUk-lk-1LN">
-                            <rect key="frame" x="162" y="6" width="91" height="32"/>
+                            <rect key="frame" x="161.66666666666666" y="6" width="91" height="32"/>
                             <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMaxY="YES"/>
                             <connections>
                                 <action selector="iconButtonPressed:" destination="4Ey-v4-VeB" eventType="touchUpInside" id="Opj-Y1-Vtg"/>
@@ -2228,9 +2228,9 @@ Um deine sicheren E-Mails auch auf einem anderen Gerät lesen zu können, muss d
         </scene>
     </scenes>
     <inferredMetricsTieBreakers>
-        <segue reference="3Wb-uL-BB5"/>
+        <segue reference="Sm1-yp-Umv"/>
         <segue reference="td8-VW-Wrt"/>
-        <segue reference="btx-4o-o0r"/>
+        <segue reference="DcR-GX-scc"/>
         <segue reference="NPH-pL-mw2"/>
         <segue reference="Fv4-FT-5gV"/>
         <segue reference="PxQ-Nb-6Fq"/>
diff --git a/enzevalos_iphone/FeedbackButtonHelper.swift b/enzevalos_iphone/FeedbackButtonHelper.swift
new file mode 100644
index 0000000000000000000000000000000000000000..1030ce821d766c870293505a286c7fc97ae7e80d
--- /dev/null
+++ b/enzevalos_iphone/FeedbackButtonHelper.swift
@@ -0,0 +1,38 @@
+//
+//  FeedbackButtonHelper.swift
+//  enzevalos_iphone
+//
+//  Created by Oliver Wiese on 18.10.19.
+//  Copyright © 2019 fu-berlin. All rights reserved.
+//
+
+import Foundation
+
+enum ViewName: String {
+    case Inbox, Read
+}
+
+class FeedbackButtonHelper {
+    
+    static let Name = NSLocalizedString("Feedback.Name", comment: "Feedback")
+    
+    static func composeFeedback(view: ViewName, navigationController: UINavigationController?) {
+        let receiver = SUPPORT_MAIL_ADR
+        let subject = String(format: NSLocalizedString("Feedback.Mail.Subject", comment: "Feedback"), view.rawValue)
+        let body = String(format: NSLocalizedString("Feedback.Mail.Body", comment: ""), view.rawValue)
+        let mail = EphemeralMail(to: NSSet(object: receiver), subject: subject, body: String(format: body, StudySettings.studyID))
+        if let navi = navigationController, let sendController = FeedbackButtonHelper.createSendViewController(navigationController: navi) {
+            sendController.prefilledMail = mail
+            sendController.isFeedback = true
+        }
+    }
+    
+    private static func createSendViewController(navigationController: UINavigationController) -> SendViewController? {
+        let mainStoryboard = UIStoryboard(name: "Main", bundle: Bundle.main)
+        if let viewController = mainStoryboard.instantiateViewController(withIdentifier: "SendViewController") as? SendViewController {
+            navigationController.pushViewController(viewController, animated: true)
+            return viewController
+        }
+        return nil
+    }
+}
diff --git a/enzevalos_iphone/SendViewController.swift b/enzevalos_iphone/SendViewController.swift
index 1f5f3a65d472b87af539a8b3eeac6cfaaf6d65cc..3dc731e96584ccfc5c2b8a34139bf2d5eb611f1b 100644
--- a/enzevalos_iphone/SendViewController.swift
+++ b/enzevalos_iphone/SendViewController.swift
@@ -69,6 +69,8 @@ class SendViewController: UIViewController {
     var contactsWithRepealedKeys: [String] = []
     var composesTravelFollowUpReminder: Bool = false
     
+    var isFeedback = false
+    
     var presentTravelDialog: Bool {
         for contact in (dataDelegate.entriesWithRepealedKeys(toText) + dataDelegate.entriesWithRepealedKeys(ccText)) {
             if !contactsWithRepealedKeys.contains(contact) && !composesTravelFollowUpReminder {
@@ -645,11 +647,19 @@ class SendViewController: UIViewController {
             }
 
             controller?.dismissAction = { [weak self] in
-                self?.dismiss(animated: true, completion: nil)
+                if self?.isFeedback ?? false{
+                    self?.navigationController?.popViewController(animated: true)
+                } else {
+                    self?.navigationController?.dismiss(animated: true, completion: nil)
+                }
             }
         }
         else {
-            self.navigationController?.dismiss(animated: true, completion: nil)
+            if isFeedback {
+                self.navigationController?.popViewController(animated: true)
+            } else {
+                self.navigationController?.dismiss(animated: true, completion: nil)
+            }
             return
         }
     }
@@ -811,7 +821,11 @@ class SendViewController: UIViewController {
                 if let delegate = self?.sendViewDelegate {
                     delegate.compositionDiscarded()
                 }
-                self?.navigationController?.dismiss(animated: true, completion: nil)
+                if self?.isFeedback ?? false {
+                    self?.navigationController?.popViewController(animated: true)
+                } else {
+                    self?.navigationController?.dismiss(animated: true, completion: nil)
+                }
             }))
             alert.addAction(UIAlertAction(title: NSLocalizedString("SaveAsDraft", comment: "save the written E-Mail as draft"), style: .default, handler: { [weak self] (action: UIAlertAction!) -> Void in
                 self?.mailHandler.createDraft(toEntrys as NSArray as! [String], ccEntrys: ccEntrys as NSArray as! [String], bccEntrys: [], subject: subject, message: message, callback: { [weak self] (error: Error?) -> Void in
@@ -821,7 +835,11 @@ class SendViewController: UIViewController {
                         if let delegate = self?.sendViewDelegate {
                             delegate.compositionSavedAsDraft()
                         }
-                        self?.navigationController?.dismiss(animated: true, completion: nil)
+                        if self?.isFeedback ?? false {
+                            self?.navigationController?.popViewController(animated: true)
+                        } else {
+                            self?.navigationController?.dismiss(animated: true, completion: nil)
+                        }
                     }
                 })
             }))
diff --git a/enzevalos_iphone/de.lproj/Localizable.strings b/enzevalos_iphone/de.lproj/Localizable.strings
index 7dcf4a385d272cd5cd86426dc695e13d57e72b1e..4bd479c6cddac4e1d75dabebd2a84fbcaa117ac5 100644
--- a/enzevalos_iphone/de.lproj/Localizable.strings
+++ b/enzevalos_iphone/de.lproj/Localizable.strings
@@ -345,3 +345,6 @@
 "Information.Links.EFF.Windows" = "Mail-Verschlüsselung Windows";
 "Information.Links.Video.DE" = "Video: einfache Erklärung";
 "Information.Links.Video.ENG" = "Video: einfache Erklärung (in englisch)";
+"Feedback.Mail.Subject" = "[Letterbox] Feedback über %@";
+"Feedback.Mail.Body" = "Wie verständlich sind die Texte [sehr verständlich: 1 bis sehr unverständlich 5]? \n\n\n Was kann verbessert werden? (von konrkete Verbesserungsvorschläge für Texte bis hin zu Hinweisen über Unklarheiten oder weitere Erklärungen.";
+"Feedback.Name" = "Feedback";
diff --git a/enzevalos_iphone/en.lproj/Localizable.strings b/enzevalos_iphone/en.lproj/Localizable.strings
index b0dfa36443637a678b5d611497403ccdd7e07b4f..43f90b08aa9776fd9743463a6349fa13f1464f11 100644
--- a/enzevalos_iphone/en.lproj/Localizable.strings
+++ b/enzevalos_iphone/en.lproj/Localizable.strings
@@ -315,5 +315,6 @@
 "Information.Links.EFF.Windows" = "Mail encryption on on Windows";
 "Information.Links.Video.DE" = "Video: simple explaination (in German)";
 "Information.Links.Video.ENG" = "Video: simple explaination";
-
-
+"Feedback.Mail.Subject" = "[Letterbox] Feedback about %@";
+"Feedback.Mail.Body" = "Wie verständlich sind die Texte [sehr verständlich: 1 bis sehr unverständlich 5]? \n\n\n Was kann verbessert werden? (von konrkete Verbesserungsvorschläge für Texte bis hin zu Hinweisen über Unklarheiten oder weitere Erklärungen.";
+"Feedback.Name" = "Feedback";