diff --git a/src/main/java/org/asamk/Signal.java b/src/main/java/org/asamk/Signal.java
index 51a35997..0a42b9bd 100644
--- a/src/main/java/org/asamk/Signal.java
+++ b/src/main/java/org/asamk/Signal.java
@@ -6,6 +6,7 @@ import org.freedesktop.dbus.DBusInterface;
 import org.freedesktop.dbus.DBusSignal;
 import org.freedesktop.dbus.exceptions.DBusException;
 import org.whispersystems.signalservice.api.push.exceptions.EncapsulatedExceptions;
+import org.whispersystems.signalservice.api.util.InvalidNumberException;
 
 import java.io.IOException;
 import java.util.List;
@@ -24,7 +25,7 @@ public interface Signal extends DBusInterface {
 
     void setContactName(String number, String name);
 
-    void setContactBlocked(String number, boolean blocked);
+    void setContactBlocked(String number, boolean blocked) throws InvalidNumberException;
 
     void setGroupBlocked(byte[] groupId, boolean blocked) throws GroupNotFoundException;
 
diff --git a/src/main/java/org/asamk/signal/commands/BlockCommand.java b/src/main/java/org/asamk/signal/commands/BlockCommand.java
index afe7c4bb..a49fc798 100644
--- a/src/main/java/org/asamk/signal/commands/BlockCommand.java
+++ b/src/main/java/org/asamk/signal/commands/BlockCommand.java
@@ -6,6 +6,7 @@ import org.asamk.signal.GroupIdFormatException;
 import org.asamk.signal.GroupNotFoundException;
 import org.asamk.signal.manager.Manager;
 import org.asamk.signal.util.Util;
+import org.whispersystems.signalservice.api.util.InvalidNumberException;
 
 public class BlockCommand implements LocalCommand {
 
@@ -28,10 +29,14 @@ public class BlockCommand implements LocalCommand {
         }
 
         for (String contact_number : ns.<String>getList("contact")) {
-            m.setContactBlocked(contact_number, true);
+            try {
+                m.setContactBlocked(contact_number, true);
+            } catch (InvalidNumberException e) {
+                System.err.println(e.getMessage());
+            }
         }
 
-        if(ns.<String>getList("group") != null) {
+        if (ns.<String>getList("group") != null) {
             for (String groupIdString : ns.<String>getList("group")) {
                 try {
                     byte[] groupId = Util.decodeGroupId(groupIdString);
diff --git a/src/main/java/org/asamk/signal/commands/UnblockCommand.java b/src/main/java/org/asamk/signal/commands/UnblockCommand.java
index 8e0a2702..be745cb0 100644
--- a/src/main/java/org/asamk/signal/commands/UnblockCommand.java
+++ b/src/main/java/org/asamk/signal/commands/UnblockCommand.java
@@ -6,6 +6,7 @@ import org.asamk.signal.GroupIdFormatException;
 import org.asamk.signal.GroupNotFoundException;
 import org.asamk.signal.manager.Manager;
 import org.asamk.signal.util.Util;
+import org.whispersystems.signalservice.api.util.InvalidNumberException;
 
 public class UnblockCommand implements LocalCommand {
 
@@ -28,10 +29,14 @@ public class UnblockCommand implements LocalCommand {
         }
 
         for (String contact_number : ns.<String>getList("contact")) {
-            m.setContactBlocked(contact_number, false);
+            try {
+                m.setContactBlocked(contact_number, false);
+            } catch (InvalidNumberException e) {
+                System.err.println(e.getMessage());
+            }
         }
 
-        if(ns.<String>getList("group") != null) {
+        if (ns.<String>getList("group") != null) {
             for (String groupIdString : ns.<String>getList("group")) {
                 try {
                     byte[] groupId = Util.decodeGroupId(groupIdString);
diff --git a/src/main/java/org/asamk/signal/manager/Manager.java b/src/main/java/org/asamk/signal/manager/Manager.java
index 4890f9f5..51c4ee59 100644
--- a/src/main/java/org/asamk/signal/manager/Manager.java
+++ b/src/main/java/org/asamk/signal/manager/Manager.java
@@ -688,7 +688,8 @@ public class Manager implements Signal {
     }
 
     @Override
-    public void setContactBlocked(String number, boolean blocked) {
+    public void setContactBlocked(String number, boolean blocked) throws InvalidNumberException {
+        number = Utils.canonicalizeNumber(number, username);
         ContactInfo contact = account.getContactStore().getContact(number);
         if (contact == null) {
             contact = new ContactInfo();
@@ -1207,7 +1208,14 @@ public class Manager implements Signal {
     }
 
     private boolean isMessageBlocked(SignalServiceEnvelope envelope, SignalServiceContent content) {
-        SignalServiceAddress source = envelope.getSourceAddress();
+        SignalServiceAddress source;
+        if (!envelope.isUnidentifiedSender() && envelope.hasSource()) {
+            source = envelope.getSourceAddress();
+        } else if (content != null) {
+            source = content.getSender();
+        } else {
+            return false;
+        }
         ContactInfo sourceContact = getContact(source.getNumber().get());
         if (sourceContact != null && sourceContact.blocked) {
             return true;
@@ -1313,8 +1321,13 @@ public class Manager implements Signal {
                 if (syncMessage.getBlockedList().isPresent()) {
                     final BlockedListMessage blockedListMessage = syncMessage.getBlockedList().get();
                     for (SignalServiceAddress address : blockedListMessage.getAddresses()) {
-                        if (address.getNumber().isPresent())
-                            setContactBlocked(address.getNumber().get(), true);
+                        if (address.getNumber().isPresent()) {
+                            try {
+                                setContactBlocked(address.getNumber().get(), true);
+                            } catch (InvalidNumberException e) {
+                                e.printStackTrace();
+                            }
+                        }
                     }
                     for (byte[] groupId : blockedListMessage.getGroupIds()) {
                         try {