diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateComment.java b/src/main/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateComment.java
index f02050b..b0c9e39 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateComment.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateComment.java
@@ -47,6 +47,12 @@
 
   @Inject private IssueExtractor issueExtractor;
 
+  private enum ItsExistenceCheckResult {
+    EXISTS,
+    DOESNT_EXIST,
+    CONNECTIVITY_FAILURE
+  }
+
   private List<CommitValidationMessage> validCommit(Project.NameKey project, RevCommit commit)
       throws CommitValidationException {
     List<CommitValidationMessage> ret = Lists.newArrayList();
@@ -63,16 +69,23 @@
           List<String> nonExistingIssueIds = Lists.newArrayList();
           client = itsFacadeFactory.getFacade(project);
           for (String issueId : issueIds) {
-            boolean exists = false;
+            ItsExistenceCheckResult existenceCheckResult;
             try {
-              exists = client.exists(issueId);
+              existenceCheckResult =
+                  client.exists(issueId)
+                      ? ItsExistenceCheckResult.EXISTS
+                      : ItsExistenceCheckResult.DOESNT_EXIST;
             } catch (IOException e) {
-              synopsis = "Failed to check whether or not issue " + issueId + " exists";
+              synopsis =
+                  "Failed to check whether or not issue "
+                      + issueId
+                      + " exists, due to connectivity issue. Commit will be accepted.";
               log.warn(synopsis, e);
               details = e.toString();
-              ret.add(commitValidationFailure(synopsis, details));
+              existenceCheckResult = ItsExistenceCheckResult.CONNECTIVITY_FAILURE;
+              ret.add(commitValidationFailure(synopsis, details, existenceCheckResult));
             }
-            if (!exists) {
+            if (existenceCheckResult == ItsExistenceCheckResult.DOESNT_EXIST) {
               nonExistingIssueIds.add(issueId);
             }
           }
@@ -95,7 +108,7 @@
             sb.append(" Issue-Tracker");
             details = sb.toString();
 
-            ret.add(commitValidationFailure(synopsis, details));
+            ret.add(commitValidationFailure(synopsis, details, ItsExistenceCheckResult.DOESNT_EXIST));
           }
         } else if (!itsConfig
             .getDummyIssuePattern()
@@ -118,7 +131,7 @@
           sb.append(" Issue-Tracker");
           details = sb.toString();
 
-          ret.add(commitValidationFailure(synopsis, details));
+          ret.add(commitValidationFailure(synopsis, details, ItsExistenceCheckResult.DOESNT_EXIST));
         }
         break;
       case OPTIONAL:
@@ -128,10 +141,12 @@
     return ret;
   }
 
-  private CommitValidationMessage commitValidationFailure(String synopsis, String details)
+  private CommitValidationMessage commitValidationFailure(
+      String synopsis, String details, ItsExistenceCheckResult existenceCheck)
       throws CommitValidationException {
     CommitValidationMessage ret = new CommitValidationMessage(synopsis + "\n" + details, false);
-    if (itsConfig.getItsAssociationPolicy() == ItsAssociationPolicy.MANDATORY) {
+    if (itsConfig.getItsAssociationPolicy() == ItsAssociationPolicy.MANDATORY
+        && existenceCheck != ItsExistenceCheckResult.CONNECTIVITY_FAILURE) {
       throw new CommitValidationException(synopsis, Collections.singletonList(ret));
     }
     return ret;
diff --git a/src/main/resources/Documentation/config-common.md b/src/main/resources/Documentation/config-common.md
index 666481f..109aba4 100644
--- a/src/main/resources/Documentation/config-common.md
+++ b/src/main/resources/Documentation/config-common.md
@@ -43,7 +43,9 @@
 
 MANDATORY
 :	 One or more issue-ids are required in the git commit message.  The git push will
-	 be rejected otherwise.
+	 be rejected otherwise. Note that in case of connectivity issues with ITS,
+	 the commit will be accepted. The client will be notified about the
+	 connectivity issue and the result.
 
 SUGGESTED
 :	 Whenever the git commit message does not contain one or more issue-ids,
diff --git a/src/test/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateCommentTest.java b/src/test/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateCommentTest.java
index d247a7c..666d463 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateCommentTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/its/base/validation/ItsValidateCommentTest.java
@@ -468,20 +468,21 @@
 
     assertEquals("Size of returned CommitValidationMessages does not match", 2, ret.size());
     assertTrue(
-        "First CommitValidationMessages does not contain " + "'Failed'",
-        ret.get(0).getMessage().contains("Failed"));
+        "First CommitValidationMessages does not contain " + "'Failed to check'",
+        ret.get(0).getMessage().contains("Failed to check"));
     assertTrue(
         "First CommitValidationMessages does not contain '4711'",
         ret.get(0).getMessage().contains("4711"));
+    assertTrue(
+        "First CommitValidationMessages contains reason of failure",
+        ret.get(0).getMessage().contains("InjectedEx1"));
     assertFalse(
         "First CommitValidationMessages contains '42', although " + "that bug exists",
         ret.get(0).getMessage().contains("42"));
     assertTrue(
         "Second CommitValidationMessages does not contain " + "'Non-existing'",
         ret.get(1).getMessage().contains("Non-existing"));
-    assertTrue(
-        "Second CommitValidationMessages does not contain '4711'",
-        ret.get(1).getMessage().contains("4711"));
+
     assertTrue(
         "Second CommitValidationMessages does not contain '42'",
         ret.get(1).getMessage().contains("42"));
@@ -489,6 +490,114 @@
     assertLogMessageContains("4711");
   }
 
+  public void testMandatoryMatchingSingleIOException()
+      throws CommitValidationException, IOException {
+    List<CommitValidationMessage> ret;
+    ItsValidateComment ivc = injector.getInstance(ItsValidateComment.class);
+    ReceiveCommand command = createMock(ReceiveCommand.class);
+    RevCommit commit = createMock(RevCommit.class);
+    CommitReceivedEvent event = newCommitReceivedEvent(command, project, null, commit, null);
+
+    expect(itsConfig.getItsAssociationPolicy())
+        .andReturn(ItsAssociationPolicy.MANDATORY)
+        .atLeastOnce();
+    expect(commit.getFullMessage()).andReturn("bug#4711").atLeastOnce();
+    expect(commit.getId()).andReturn(commit).anyTimes();
+    expect(commit.getName()).andReturn("TestCommit").anyTimes();
+    expect(issueExtractor.getIssueIds("bug#4711")).andReturn(new String[] {"4711"}).atLeastOnce();
+    expect(itsFacadeFactory.getFacade(project.getNameKey())).andReturn(itsFacade).anyTimes();
+    expect(itsFacade.exists("4711")).andThrow(new IOException("InjectedEx1")).atLeastOnce();
+
+    replayMocks();
+
+    ret = ivc.onCommitReceived(event);
+
+    assertEquals("Size of returned CommitValidationMessages does not match", 1, ret.size());
+    assertTrue(
+        "First CommitValidationMessages does not contain " + "'Failed to check'",
+        ret.get(0).getMessage().contains("Failed to check"));
+    assertTrue(
+        "First CommitValidationMessages does not contain '4711'",
+        ret.get(0).getMessage().contains("4711"));
+    assertTrue(
+        "First CommitValidationMessages contains reason of failure",
+        ret.get(0).getMessage().contains("InjectedEx1"));
+
+    assertLogMessageContains("4711");
+  }
+
+  public void testMandatoryMatchingMultipleIOExceptionIsNonExisting() throws IOException {
+    List<CommitValidationMessage> ret;
+    ItsValidateComment ivc = injector.getInstance(ItsValidateComment.class);
+    ReceiveCommand command = createMock(ReceiveCommand.class);
+    RevCommit commit = createMock(RevCommit.class);
+    CommitReceivedEvent event = newCommitReceivedEvent(command, project, null, commit, null);
+
+    expect(itsConfig.getItsAssociationPolicy())
+        .andReturn(ItsAssociationPolicy.MANDATORY)
+        .atLeastOnce();
+    expect(commit.getFullMessage()).andReturn("bug#4711, bug#42").atLeastOnce();
+    expect(commit.getId()).andReturn(commit).anyTimes();
+    expect(commit.getName()).andReturn("TestCommit").anyTimes();
+    expect(issueExtractor.getIssueIds("bug#4711, bug#42"))
+        .andReturn(new String[] {"4711", "42"})
+        .atLeastOnce();
+    expect(itsFacadeFactory.getFacade(project.getNameKey())).andReturn(itsFacade).anyTimes();
+    expect(itsFacade.exists("4711")).andThrow(new IOException("InjectedEx1")).atLeastOnce();
+    expect(itsFacade.exists("42")).andReturn(false).atLeastOnce();
+
+    replayMocks();
+
+    try {
+      ivc.onCommitReceived(event);
+      fail("onCommitReceived did not throw any exception");
+    } catch (CommitValidationException e) {
+      assertLogMessageContains("Failed to check whether or not issue 4711 exists");
+      assertTrue(
+          "Message of thrown CommitValidationException does not " + "contain 'Non-existing'",
+          e.getMessage().contains("Non-existing"));
+    }
+  }
+
+  public void testMandatoryMatchingMultipleIOExceptionExisting()
+      throws CommitValidationException, IOException {
+    List<CommitValidationMessage> ret;
+    ItsValidateComment ivc = injector.getInstance(ItsValidateComment.class);
+    ReceiveCommand command = createMock(ReceiveCommand.class);
+    RevCommit commit = createMock(RevCommit.class);
+    CommitReceivedEvent event = newCommitReceivedEvent(command, project, null, commit, null);
+
+    expect(itsConfig.getItsAssociationPolicy())
+        .andReturn(ItsAssociationPolicy.MANDATORY)
+        .atLeastOnce();
+    expect(commit.getFullMessage()).andReturn("bug#4711, bug#42").atLeastOnce();
+    expect(commit.getId()).andReturn(commit).anyTimes();
+    expect(commit.getName()).andReturn("TestCommit").anyTimes();
+    expect(issueExtractor.getIssueIds("bug#4711, bug#42"))
+        .andReturn(new String[] {"4711", "42"})
+        .atLeastOnce();
+    expect(itsFacadeFactory.getFacade(project.getNameKey())).andReturn(itsFacade).anyTimes();
+    expect(itsFacade.exists("4711")).andThrow(new IOException("InjectedEx1")).atLeastOnce();
+    expect(itsFacade.exists("42")).andReturn(true).atLeastOnce();
+
+    replayMocks();
+
+    ret = ivc.onCommitReceived(event);
+
+    assertEquals("Size of returned CommitValidationMessages does not match", 1, ret.size());
+    assertTrue(
+        "First CommitValidationMessages does not contain " + "'Failed to check'",
+        ret.get(0).getMessage().contains("Failed to check"));
+    assertTrue(
+        "First CommitValidationMessages does not contain '4711'",
+        ret.get(0).getMessage().contains("4711"));
+    assertTrue(
+        "First CommitValidationMessages contains reason of failure",
+        ret.get(0).getMessage().contains("InjectedEx1"));
+
+    assertLogMessageContains("4711");
+  }
+
   public void assertEmptyList(List<CommitValidationMessage> list) {
     if (!list.isEmpty()) {
       StringBuffer sb = new StringBuffer();