diff --git a/frontend/src/utils/exam-correct/exam-correct.js b/frontend/src/utils/exam-correct/exam-correct.js
index 70a9bdb63..0e57d86e3 100644
--- a/frontend/src/utils/exam-correct/exam-correct.js
+++ b/frontend/src/utils/exam-correct/exam-correct.js
@@ -19,16 +19,29 @@ const EXAM_CORRECT_HEADERS = {
 const EXAM_CORRECT_IDENT = 'uw-exam-correct';
 const EXAM_CORRECT_PART_INPUT_ATTR = 'uw-exam-correct--part-input';
 const EXAM_CORRECT_SEND_BTN_ID = 'exam-correct__send-btn';
-const EXAM_CORRECT_PARTICIPANT_INPUT_ID = 'exam-correct__user';
+const EXAM_CORRECT_USER_INPUT_ID = 'exam-correct__user';
+const EXAM_CORRECT_USER_INPUT_STATUS_ID = 'exam-correct__user-status';
 const EXAM_CORRECT_USER_INPUT_CANDIDATES_ID = 'exam-correct__user-candidates';
 const EXAM_CORRECT_INPUT_BODY_ID = 'exam-correct__new';
-const EXAM_CORRECT_PARTICIPANT_ATTR = 'exam-correct--user';
+const EXAM_CORRECT_USER_ATTR = 'exam-correct--user-id';
+const EXAM_CORRECT_USER_DNAME_ATTR = 'exam-correct--user-dname';
 
 const INPUT_EMPTY_CLASS = 'input--invalid';
 
 // TODO get from settings
 const MOMENT_FORMAT = 'DD.MM.YY HH:mm:ss';
 
+// TODO 1 for debugging only, 3 would be a better choice
+const USER_VALIDATION_MIN_LENGTH = 1;
+
+const STATUS = {
+  NONE: 0,
+  SUCCESS: 1,
+  AMBIGUOUS: 2,
+  ERROR: 3,
+  LOADING: 4,
+};
+
 
 @Utility({
   selector: `table[${EXAM_CORRECT_IDENT}]`,
@@ -41,6 +54,7 @@ export class ExamCorrect {
 
   _sendBtn;
   _userInput;
+  _userInputStatus;
   _userInputCandidates;
   _partInputs;
 
@@ -56,7 +70,8 @@ export class ExamCorrect {
     this._element = element;
     this._app = app;
     this._sendBtn = document.getElementById(EXAM_CORRECT_SEND_BTN_ID);
-    this._userInput = document.getElementById(EXAM_CORRECT_PARTICIPANT_INPUT_ID);
+    this._userInput = document.getElementById(EXAM_CORRECT_USER_INPUT_ID);
+    this._userInputStatus = document.getElementById(EXAM_CORRECT_USER_INPUT_STATUS_ID);
     this._userInputCandidates = document.getElementById(EXAM_CORRECT_USER_INPUT_CANDIDATES_ID);
     this._partInputs = [...this._element.querySelectorAll(`input[${EXAM_CORRECT_PART_INPUT_ATTR}]`)];
 
@@ -68,6 +83,10 @@ export class ExamCorrect {
       this._userInput.addEventListener('focusout', this._validateUserInput.bind(this));
     else throw new Error('ExamCorrect utility could not detect user input!');
 
+    if (!this._userInputStatus) {
+      throw new Error('ExamCorrect utility could not detect user input status element!');
+    }
+
     if (!this._userInputCandidates) {
       throw new Error('ExamCorrect utility could not detect user input candidate list!');
     }
@@ -77,17 +96,34 @@ export class ExamCorrect {
     this._sendBtn.removeEventListener('click', this._sendCorrectionHandler);
     this._userInput.removeEventListener('change', this._validateUserInput);
     this._userInput.removeEventListener('input', this._removeInputEmptyClassHandler);
+    // TODO destroy handlers on user input candidate elements
   }
 
   _validateUserInput() {
     const user = this._userInput.value;
 
-    if (!user) return;
+    // do nothing in case of empty or too short input
+    if (!user || user.length < USER_VALIDATION_MIN_LENGTH) {
+      removeAllChildren(this._userInputCandidates);
+      setStatus(this._userInputStatus, STATUS.NONE);
+      return;
+    }
+
+    if (this._userInput.getAttribute(EXAM_CORRECT_USER_ATTR) !== null) {
+      if (this._userInput.value === this._userInput.getAttribute(EXAM_CORRECT_USER_DNAME_ATTR)) {
+        setStatus(this._userInputStatus, STATUS.NONE);
+        return;
+      } else {
+        this._userInput.removeAttribute(EXAM_CORRECT_USER_ATTR);
+      }
+    }
+
+    setStatus(this._userInputStatus, STATUS.LOADING);
 
     const body = {
-      name:    user,
+      name: user,
       results: {},
-      op:      false,
+      op: false,
     };
 
     this._app.httpClient.post({
@@ -103,9 +139,7 @@ export class ExamCorrect {
     });
   }
 
-  _sendCorrectionHandler(event) {
-    console.log('WIP _sendCorrectionHandler', event);
-
+  _sendCorrectionHandler() {
     // refocus user input element for convenience
     this._userInput.focus();
 
@@ -119,15 +153,19 @@ export class ExamCorrect {
     }
 
     const results = {};
-    this._partInputs.forEach((input) => {
-      if (input.value && !isNaN(input.value)) {
-        // TODO instead of ignoring NaN values, abort send and add error class to corresponding input
-        // (latter is optional)
+    for (const input of this._partInputs) {
+      if (input.value) {
+        if (isNaN(input.value)) {
+          input.classList.add('input--invalid');
+          input.focus();
+          return;
+        }
+
         const partKey = input.getAttribute(EXAM_CORRECT_PART_INPUT_ATTR);
         if (!partKey) throw new Error('Exam part input without part attribute!');
         results[partKey] = parseFloat(input.value);
       }
-    });
+    }
 
     // abort send if there are no results (after validation)
     if (Object.keys(results).length <= 0) return;
@@ -141,7 +179,7 @@ export class ExamCorrect {
     dateTD.setAttribute('date', moment());
     const userTD = document.createElement('TD');
     userTD.appendChild(document.createTextNode(user));
-    userTD.setAttribute(EXAM_CORRECT_PARTICIPANT_ATTR, user);
+    userTD.setAttribute(EXAM_CORRECT_USER_ATTR, user);
     const partTDs = this._partInputs.map((input) => {
       const partTD = document.createElement('TD');
       const partKey = input.getAttribute(EXAM_CORRECT_PART_INPUT_ATTR);
@@ -163,6 +201,7 @@ export class ExamCorrect {
     // clear input values on validation success
     // TODO only clear input on post success
     [this._userInput, ...this._partInputs].forEach(clearInput);
+    setStatus(this._userInputStatus, STATUS.NONE);
 
     const body = {
       name: user,
@@ -189,29 +228,49 @@ export class ExamCorrect {
     if (response) {
       if (response.status === 'no-op') {
         if (response.users) {
-          // TODO directly replace input value and add attr if list contains only one element
+          // delete candidate list entries from previous requests
+          removeAllChildren(this._userInputCandidates);
 
-          // TODO add event handler on links -> display name as input value and set id as attribute
+          // show error if there are no matches for this input
+          if (response.users.length === 0) {
+            setStatus(this._userInputStatus, STATUS.FAILURE);
+            return;
+          }
+
+          // directly accept response if there is exactly one candidate (input not ambiguous)
+          if (response.users.length === 1) {
+            const candidate = response.users[0];
+            this._userInput.value = candidate['display-name'];
+            this._userInput.setAttribute(EXAM_CORRECT_USER_ATTR, candidate.id);
+            this._userInput.setAttribute(EXAM_CORRECT_USER_DNAME_ATTR, candidate['display-name']);
+            setStatus(this._userInputStatus, STATUS.SUCCESS);
+            return;
+          }
+
+          setStatus(this._userInputStatus, STATUS.AMBIGUOUS);
           // TODO how to destroy candidate handlers?
           response.users.forEach((userCandidate) => {
             const candidateItem = document.createElement('li');
-            userAsInnerHTML(candidateItem, userCandidate);
-            candidateItem.setAttribute(EXAM_CORRECT_PARTICIPANT_ATTR, userCandidate.id);
+            candidateItem.innerHTML = userToHTML(userCandidate);
+            candidateItem.setAttribute(EXAM_CORRECT_USER_ATTR, userCandidate.id);
             
             const acceptCandidateHandler = () => {
-              console.log('candidate accepted');
               this._userInput.value = userCandidate['display-name'] || userCandidate.surname || userCandidate['mat-nr'];
-              this._userInput.setAttribute(EXAM_CORRECT_PARTICIPANT_ATTR, userCandidate.id);
+              this._userInput.setAttribute(EXAM_CORRECT_USER_ATTR, userCandidate.id);
               
-              // remove all candidates
-              while (this._userInputCandidates.firstChild) {
-                this._userInputCandidates.removeChild(this._userInputCandidates.firstChild);
-              }
+              // remove all candidates on accept
+              removeAllChildren(this._userInputCandidates);
+
+              setStatus(this._userInputStatus, STATUS.SUCCESS);
+
+              // TODO focus first part result input element for convenience
             };
-            candidateItem.addEventListener('click', acceptCandidateHandler, { once: true });
+            candidateItem.addEventListener('click', acceptCandidateHandler);
 
             this._userInputCandidates.appendChild(candidateItem);
           });
+        } else {
+          setStatus(this._userInputStatus, STATUS.FAILURE);
         }
 
         return;
@@ -219,18 +278,16 @@ export class ExamCorrect {
     
       for (let row of [...this._element.rows]) {
         const userElem = row.cells.item(1);
-        const userIdent = userElem && userElem.getAttribute(EXAM_CORRECT_PARTICIPANT_ATTR);
+        const userIdent = userElem && userElem.getAttribute(EXAM_CORRECT_USER_ATTR);
         if (userIdent === user) {
-          let faIcon, ecClass;
+          let status = STATUS.ERROR;
           switch (response.status) {
             // TODO fetch update time from response and replace
             case 'success':
-              faIcon = 'fa-check';
-              ecClass = 'exam-correct--success';
+              status = STATUS.SUCCESS;
               if (response.user) {
-                userElem.setAttribute(EXAM_CORRECT_PARTICIPANT_ATTR, response.user.id);
-                userElem.innerHTML = '';
-                userAsInnerHTML(userElem, response.user);
+                userElem.setAttribute(EXAM_CORRECT_USER_ATTR, response.user.id);
+                userElem.innerHTML = userToHTML(response.user);
               }
               // TODO replace results with results from response
               // TODO set edit button visibility
@@ -238,27 +295,21 @@ export class ExamCorrect {
             case 'ambiguous':
               // TODO show tooltip with error message
               // TODO set edit button visibility
-              faIcon = 'fa-times';
-              ecClass = 'exam-correct--error';
-              // TODO show users
+              status = STATUS.AMBIGUOUS;
               if (response.users) {
-                showUsers(userElem, response.users);
+                this._showUserList(userElem, response.users);
               }
               break;
             case 'failure':
-              faIcon = 'fa-times';
-              ecClass = 'exam-correct--error';
+              status = STATUS.FAILURE;
               break;
             default:
               // TODO show tooltip with 'invalid response'
               // TODO set edit button visibility
               console.error('Invalid response');
-              faIcon = 'fa-times';
-              ecClass = 'exam-correct--error';
           }
           row.querySelectorAll('.exam-correct--loading').forEach((elem) => {
-            elem.classList.remove('exam-correct--loading');
-            elem.classList.add('fa', faIcon, ecClass);
+            setStatus(elem, status);
           });
           break;
         }
@@ -275,30 +326,76 @@ export class ExamCorrect {
     }
   }
 
+  // TODO better name
+  _showUserList(elem, users) {
+    if (users) {
+      removeAllChildren(elem);
+      const list = document.createElement('UL');
+      for (const user of users) {
+        const listItem = document.createElement('LI');
+        listItem.innerHTML = userToHTML(user);
+        listItem.setAttribute(EXAM_CORRECT_USER_ATTR, user.id);
+        listItem.setAttribute(EXAM_CORRECT_USER_DNAME_ATTR, user['display-name']);
+        // TODO destroy event handler
+        //const acceptCandidateHandler = () => {
+        //  elem.innerHTML = userToHTML(user);
+        //};
+        //listItem.addEventListener('click', acceptCandidateHandler);
+        list.appendChild(listItem);
+      }
+      elem.appendChild(list);
+    } else {
+      console.error('Unable to show users from invalid response');
+    }
+  }
+
 }
 
 // TODO move to general util section?
 function clearInput(inputElement) {
   inputElement.value = null;
 }
+function removeAllChildren(element) {
+  while (element.firstChild) {
+    element.removeChild(element.firstChild);
+  }
+}
 
-function userAsInnerHTML(elem, user) {
+
+function userToHTML(user) {
   if (user && user['display-name'] && user['surname']) {
-    elem.innerHTML += user['display-name'].replace(new RegExp(user['surname']), `<strong>${user['surname']}</strong>`) + (user['mat-nr'] ? ` (${user['mat-nr']})` : '');
+    return user['display-name'].replace(new RegExp(user['surname']), `<strong>${user['surname']}</strong>`) + (user['mat-nr'] ? ` (${user['mat-nr']})` : '');
   } else {
     console.error('Unable to format invalid user response');
+    return '';
   }
 }
 
-// TODO better name
-function showUsers(elem, users) {
-  elem.innerHTML = '';
-  if (users) {
-    for (const user of users) {
-      userAsInnerHTML(elem, user);
-      elem.innerHTML += '<br/>';
-    }
-  } else {
-    console.error('Unable to show users from invalid response');
+function setStatus(elem, status) {
+  const successClasses = ['fas', 'fa-fw', 'fa-check', 'exam-correct--success'];
+  const ambiguousClasses = ['fas', 'fa-fw', 'fa-question', 'exam-correct--ambiguous'];
+  const errorClasses = ['fas', 'fa-fw', 'fa-times', 'exam-correct--error'];
+  const loadingClasses = ['fas', 'fa-fw', 'fa-spinner-third', 'exam-correct--loading'];
+
+  elem.classList.remove(...successClasses, ...ambiguousClasses, ...errorClasses, ...loadingClasses);
+
+  switch (status) {
+    case STATUS.NONE:
+      break;
+    case STATUS.SUCCESS:
+      elem.classList.add(...successClasses);
+      break;
+    case STATUS.AMBIGUOUS:
+      elem.classList.add(...ambiguousClasses);
+      break;
+    case STATUS.FAILURE:
+      elem.classList.add(...errorClasses);
+      break;
+    case STATUS.LOADING:
+      elem.classList.add(...loadingClasses);
+      break;
+    default:
+      console.error('Invalid user input status!');
   }
 }
+
diff --git a/frontend/src/utils/exam-correct/exam-correct.sass b/frontend/src/utils/exam-correct/exam-correct.sass
index 63fd21145..821feecd2 100644
--- a/frontend/src/utils/exam-correct/exam-correct.sass
+++ b/frontend/src/utils/exam-correct/exam-correct.sass
@@ -1,18 +1,25 @@
-#exam-correct__participant.input--invalid
+input.input--invalid
   border: 2px solid var(--color-error)
 
+.exam-correct--input-status
+  $exam-correct--input-status-margin: 10px
+
+  input
+    width: calc(100% - 18em/14 - #{$exam-correct--input-status-margin})
+  i
+    margin-left: $exam-correct--input-status-margin
+
 .exam-correct--success
   color: var(--color-success)
 
+.exam-correct--ambiguous
+  color: var(--color-warning)
+
 .exam-correct--error
   color: var(--color-error)
 
+// TODO move to general app style
 .exam-correct--loading
-  border: 3px solid var(--color-grey-light)
-  border-top: 3px solid var(--color-primary)
-  border-radius: 50%
-  width: 20px
-  height: 20px
   animation: spin 2s linear infinite
 
 @keyframes spin
diff --git a/messages/uniworx/de-de-formal.msg b/messages/uniworx/de-de-formal.msg
index 88f55b4ec..e47822fed 100644
--- a/messages/uniworx/de-de-formal.msg
+++ b/messages/uniworx/de-de-formal.msg
@@ -1405,8 +1405,8 @@ ExamCorrectHeadStatus: Status
 
 ExamCorrectButtonSend: Senden
 
-ExamCorrectErrorMultipleMatchingParticipants: Dem Identifikator konnten mehrere Pruefungsteilnehmer zugeordnet werden.
-ExamCorrectErrorNoMatchingParticipants: Dem Identifikator konnte kein Pruefungsteilnehmer zugeordnet werden.
+ExamCorrectErrorMultipleMatchingParticipants: Dem Identifikator konnten mehrere Prüfungsteilnehmer zugeordnet werden.
+ExamCorrectErrorNoMatchingParticipants: Dem Identifikator konnte kein Prüfungsteilnehmer zugeordnet werden.
 
 SubmissionUserInvitationAccepted shn@SheetName: Sie wurden als Mitabgebende(r) für eine Abgabe zu #{shn} eingetragen
 SubmissionUserInvitationDeclined shn@SheetName: Sie haben die Einladung, Mitabgebende(r) für #{shn} zu werden, abgelehnt
@@ -2289,4 +2289,4 @@ ExternalExamUserMustBeStaff: Sie selbst müssen stets assoziierte Person sein, f
 ExternalExamCourseExists: Der angegebene Kurs existiert im System. Prüfungen sollten daher direkt beim Kurs (statt extern) hinterlegt werden.
 ExternalExamExists coursen@CourseName examn@ExamName: Prüfung „#{examn}“ für Kurs „#{coursen}“ existiert bereits.
 ExternalExamCreated coursen@CourseName examn@ExamName: Prüfung „#{examn}“ für Kurs „#{coursen}“ erfolgreich angelegt.
-ExternalExamEdited coursen@CourseName examn@ExamName: Prüfung „#{examn}“ für Kurs „#{coursen}“ erfolgreich bearbeitet.
\ No newline at end of file
+ExternalExamEdited coursen@CourseName examn@ExamName: Prüfung „#{examn}“ für Kurs „#{coursen}“ erfolgreich bearbeitet.
diff --git a/templates/exam-correct.hamlet b/templates/exam-correct.hamlet
index b825dda09..9abfdc8d7 100644
--- a/templates/exam-correct.hamlet
+++ b/templates/exam-correct.hamlet
@@ -25,8 +25,9 @@ $newline never
       <tbody #exam-correct__new>
         <tr .table__row>
           <td .table__td>
-          <td .table__td>
+          <td .table__td .exam-correct--input-status>
             <input #exam-correct__user type="text">
+            <i #exam-correct__user-status .fas .fa-fw>
             <ul #exam-correct__user-candidates>
           $forall ExamPart{examPartNumber} <- examParts
             <td .table__td>