diff --git a/functions/imap_general.php b/functions/imap_general.php
index a80993503..8a7319148 100755
--- a/functions/imap_general.php
+++ b/functions/imap_general.php
@@ -258,6 +258,8 @@
  			    $sqimap_capabilities[$cap_list[0]] = TRUE;
 		}
 	}
+	if (! isset($sqimap_capabilities[$capability]))
+	   return false;
 	return $sqimap_capabilities[$capability];
 }