diff --git a/messaging-core/src/main/java/org/fenixedu/messaging/core/ui/MessagingController.java b/messaging-core/src/main/java/org/fenixedu/messaging/core/ui/MessagingController.java
index f5b6d14..75ece7b 100644
--- a/messaging-core/src/main/java/org/fenixedu/messaging/core/ui/MessagingController.java
+++ b/messaging-core/src/main/java/org/fenixedu/messaging/core/ui/MessagingController.java
@@ -119,6 +119,7 @@ public String viewSender(final Model model, @PathVariable final Sender sender,
         }
         info.addProperty("html", sender.getHtmlEnabled());
         info.addProperty("attachmentsEnabled", sender.getAttachmentsEnabled());
+        info.addProperty("optInRequired", sender.getOptInRequired());
         return new ResponseEntity<>(info.toString(), HttpStatus.OK);
     }
 
diff --git a/messaging-core/src/main/webapp/WEB-INF/messaging/newMessage.jsp b/messaging-core/src/main/webapp/WEB-INF/messaging/newMessage.jsp
index 685575a..c4f0d2c 100644
--- a/messaging-core/src/main/webapp/WEB-INF/messaging/newMessage.jsp
+++ b/messaging-core/src/main/webapp/WEB-INF/messaging/newMessage.jsp
@@ -41,6 +41,16 @@ ${portal.toolkit()}
 	</div>
 </c:if>
 
+<div class="row">
+	<div id="nonOptInRequiredDiv" class="col-sm-8 col-sm-offset-2 alert alert-warning">
+		<h4>
+			<span class="glyphicon glyphicon-info-sign" aria-hidden="true"></span>
+			<spring:message code="title.disclaimer.non.optin.required.sender.selected"/>
+		</h4>
+		<p><spring:message code="disclaimer.non.optin.required.sender.selected"/></p>
+	</div>
+</div>
+
 <spring:eval expression="T(org.fenixedu.messaging.core.domain.Sender).available()" var="senders"/>
 <spring:eval expression="T(org.fenixedu.bennu.core.util.CoreConfiguration).supportedLocales()" var="locales"/>
 <form:form modelAttribute="messageBean" role="form" class="form-horizontal" action="${pageContext.request.contextPath}/messaging/message" method="post">
@@ -217,6 +227,7 @@ ${portal.toolkit()}
             $('#replyTo').val(info.replyTo);
             toggleHtml(info);
             toggleAttachments(info);
+            toggleNonOptInRequiredDisclaimer(info);
         });
     }
 
@@ -243,6 +254,16 @@ ${portal.toolkit()}
         }
     }
 
+    function toggleNonOptInRequiredDisclaimer(info) {
+        var nonOptInRequiredDisclaimerEl = $('#nonOptInRequiredDiv');
+        if (!info.optInRequired) {
+            nonOptInRequiredDisclaimerEl.show();
+        }
+        else {
+            nonOptInRequiredDisclaimerEl.hide();
+        }
+    }
+
 	var addAttachmentEl = $('#addAttachment');
 	addAttachmentEl.change(function(event){
         var files = event.target.files;
diff --git a/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_en.properties b/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_en.properties
index b75b843..20c803d 100644
--- a/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_en.properties
+++ b/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_en.properties
@@ -15,6 +15,9 @@ action.view = View Details
 action.subscribe = Subscribe
 action.unsubscribe = Unsubscribe
 
+disclaimer.non.optin.required.sender.selected = The currently selected sender is a non opt-in required sender, which means that all messages sent by this sender will reach all members of the selected recipients.
+title.disclaimer.non.optin.required.sender.selected = Disclaimer - Non Opt-In Required Sender Selected
+
 error.message.not.sent = Message could not be sent:
 error.template.not.saved = Message template could not be saved:
 error.template.undeclared = Message template is undeclared.
diff --git a/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_pt.properties b/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_pt.properties
index f849b51..0cdfac3 100644
--- a/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_pt.properties
+++ b/messaging-core/src/main/webapp/WEB-INF/resources/MessagingResources_pt.properties
@@ -104,5 +104,7 @@ title.templates.config = Configuração de Modelos de Mensagem
 title.template = Modelo de Mensagem
 title.template.edit = Editar Modelo de Mensagem
 label.message.attachments=Anexos
+disclaimer.non.optin.required.sender.selected = O remetente selecionado não requer subscrição, o que signfica que todas as mensagens enviadas por este remetente irão chegar a todos os membros dos destinatários selecionados.
+title.disclaimer.non.optin.required.sender.selected = Disclaimer - Remetente Selecionado Não Requer Subscrição
 label.sender.lastMessageSent=Última Mensagem Enviada