diff --git a/mozilla/mailnews/base/public/nsIMsgIncomingServer.idl b/mozilla/mailnews/base/public/nsIMsgIncomingServer.idl
index 8e7081eca81..69942a1ef59 100644
--- a/mozilla/mailnews/base/public/nsIMsgIncomingServer.idl
+++ b/mozilla/mailnews/base/public/nsIMsgIncomingServer.idl
@@ -140,6 +140,9 @@ interface nsIMsgIncomingServer : nsISupports {
   wstring toString();
 
   attribute boolean isSecure;
+
+  /* used for comparing nsIMsgIncomingServers */
+  boolean equals(in nsIMsgIncomingServer server);
 };
 
 %{C++
diff --git a/mozilla/mailnews/base/util/nsMsgIncomingServer.cpp b/mozilla/mailnews/base/util/nsMsgIncomingServer.cpp
index 3044553492f..19d97f60443 100644
--- a/mozilla/mailnews/base/util/nsMsgIncomingServer.cpp
+++ b/mozilla/mailnews/base/util/nsMsgIncomingServer.cpp
@@ -707,6 +707,33 @@ nsMsgIncomingServer::GetLocalStoreType(char **aResult)
     return NS_ERROR_UNEXPECTED;
 }
 
+NS_IMETHODIMP
+nsMsgIncomingServer::Equals(nsIMsgIncomingServer *server, PRBool *_retval)
+{
+    nsresult rv;
+
+    NS_ENSURE_ARG_POINTER(server);
+    NS_ENSURE_ARG_POINTER(_retval);
+
+    nsXPIDLCString key1;
+    nsXPIDLCString key2;
+
+    rv = GetKey(getter_Copies(key1));
+    if (NS_FAILED(rv)) return rv;
+
+    rv = server->GetKey(getter_Copies(key2));
+    if (NS_FAILED(rv)) return rv;
+
+    // compare the server keys
+    if (PL_strcmp((const char *)key1,(const char *)key2)) {
+        *_retval = PR_FALSE;
+    }
+    else {
+        *_retval = PR_TRUE;
+    }
+    return rv;
+}
+
 // use the convenience macros to implement the accessors
 NS_IMPL_SERVERPREF_STR(nsMsgIncomingServer, HostName, "hostname");
 NS_IMPL_SERVERPREF_INT(nsMsgIncomingServer, Port, "port");