Index: src/java/org/sakaiproject/site/tool/helper/participant/impl/SiteAddParticipantHandler.java
===================================================================
--- src/java/org/sakaiproject/site/tool/helper/participant/impl/SiteAddParticipantHandler.java	(revision 63355)
+++ src/java/org/sakaiproject/site/tool/helper/participant/impl/SiteAddParticipantHandler.java	(working copy)
@@ -11,6 +11,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.commons.validator.EmailValidator;
 import org.sakaiproject.authz.api.AuthzGroup;
 import org.sakaiproject.authz.api.AuthzGroupService;
 import org.sakaiproject.authz.api.AuthzPermissionException;
@@ -794,6 +795,11 @@
 						targettedMessageList.addMessage(new TargettedMessage("java.emailaddress",
 		                new Object[] { nonOfficialAccount }, 
 		                TargettedMessage.SEVERITY_ERROR));
+					} else if (!isValidMail(nonOfficialAccount)) {
+						// must be a valid email address
+						targettedMessageList.addMessage(new TargettedMessage("java.emailaddress",
+				                new Object[] { nonOfficialAccount }, 
+				                TargettedMessage.SEVERITY_ERROR));
 					} else {
 						Participant participant = new Participant();
 						try {
@@ -918,8 +924,24 @@
 			}
 		}
 		return true;
+		
+		
 	}
     
+	private boolean isValidMail(String email) {
+
+
+		if (email == null || email.equals(""))
+			return false;
+		
+		
+		email = email.trim();
+		
+		EmailValidator ev = EmailValidator.getInstance();
+		return ev.isValid(email);
+		
+	}
+	
 	private Vector<Participant> removeDuplicateParticipants(List<Participant> pList) {
 		// check the uniqueness of list member
 		Set<String> s = new HashSet<String>();
Index: pom.xml
===================================================================
--- pom.xml	(revision 63355)
+++ pom.xml	(working copy)
@@ -95,6 +95,16 @@
       <artifactId>commons-logging</artifactId>
       <version>1.0.4</version>
     </dependency>
+    <dependency>
+    	<groupId>commons-validator</groupId>
+    	<artifactId>commons-validator</artifactId>
+    	<version>1.3.1</version>
+    </dependency>
+    <dependency>
+    	<groupId>oro</groupId>
+    	<artifactId>oro</artifactId>
+    	<version>2.0.8</version>
+    </dependency>
   </dependencies>
   <build>
     <sourceDirectory>src/java</sourceDirectory>