diff -ru TYPO3core_orig_cvs/typo3/sysext/cms/tslib/class.tslib_content.php TYPO3core_patch1590/typo3/sysext/cms/tslib/class.tslib_content.php
--- TYPO3core_orig_cvs/typo3/sysext/cms/tslib/class.tslib_content.php	2005-10-21 10:06:59.000000000 +0200
+++ TYPO3core_patch1590/typo3/sysext/cms/tslib/class.tslib_content.php	2005-10-25 16:53:10.000000000 +0200
@@ -4972,6 +4972,7 @@
 					}
 					$this->lastTypoLinkTarget = $target;
 					$finalTagParts['url']=$this->lastTypoLinkUrl;
+					$this->typoLink_registerExternal($this->lastTypoLinkUrl,$linktxt);
 					$finalTagParts['targetParams'] = $target ? ' target="'.$target.'"' : '';
 					$finalTagParts['TYPE']='url';
 				} elseif ($containsSlash || $isLocalFile)	{	// file (internal)
@@ -4991,6 +4992,7 @@
 						$finalTagParts['TYPE'] = 'file';
 					} else {
 						$GLOBALS['TT']->setTSlogMessage("typolink(): File '".$splitLinkParam[0]."' did not exist, so '".$linktxt."' was not linked.",1);
+						$this->typoLink_error($splitLinkParam[0], 'file', $linktxt);
 						return $linktxt;
 					}
 	 			} else {	// integer or alias (alias is without slashes or periods or commas, that is 'nospace,alphanum_x,lower,unique' according to definition in $TCA!)
@@ -5051,6 +5053,7 @@
 							$page = $GLOBALS['TSFE']->sys_page->getPage($mount_info['mount_pid'],$disableGroupAccessCheck);
 							if (!count($page))	{
 								$GLOBALS['TT']->setTSlogMessage("typolink(): Mount point '".$mount_info['mount_pid']."' was not available, so '".$linktxt."' was not linked.",1);
+								$this->typoLink_error($mount_info['mount_pid'], 'mount', $linktxt);
 								return $linktxt;
 							}
 							$MPvarAcc['re-map'] = $mount_info['MPvar'];
@@ -5121,6 +5124,7 @@
 						$finalTagParts['TYPE']='page';
 					} else {
 						$GLOBALS['TT']->setTSlogMessage("typolink(): Page id '".$link_param."' was not found, so '".$linktxt."' was not linked.",1);
+						$this->typoLink_error($link_param, 'page', $linktxt);
 						return $linktxt;
 					}
 				}
@@ -5166,6 +5170,37 @@
 	}
 
 	/**
+	 * here, a hook function can be called which handles all the things which should happen when a link is not found or a link *might* be not found
+	 * 
+	 * @param	string		Target of the link, can be an integer for pages, or a file reference
+	 * @param	string		either 'file', 'page', or 'mount', or 'external'
+	 * @param	string		linked text
+	 * @param	boolean		has to be set to zero if the link still needs to be checked (in the backend) - needed for external links
+	 * @private
+	 */
+	function typoLink_error($linkurl,$type,$linktext,$is_error = 1) {
+		global $TYPO3_CONF_VARS;
+		if (is_array($TYPO3_CONF_VARS['SC_OPTIONS']['tslib/class.tslib_content.php']['typoLink_error']))	{
+			$params = array('target' => $linkurl, 'type' => $type, 'linktext' => $linktext, 'is_error' => $is_error);
+			$fakeThis = FALSE;
+			foreach($TYPO3_CONF_VARS['SC_OPTIONS']['tslib/class.tslib_content.php']['typoLink_error'] as $hookMethod)	{
+				t3lib_div::callUserFunction($hookMethod,$params,$fakeThis);
+			}
+		}
+	}
+
+	/**
+	 * wrapper for typoLink_error for external links. This function is called for all external links because they need to be checked seperately in the backend.
+	 * 
+	 * @param	string		Target of the link, can be an integer for pages, or a file reference
+	 * @param	string		linked text
+	 * @private
+	 */
+	function typoLink_registerExternal($linkurl,$linktext) {
+		$this->typoLink_error($linkurl,'external',$linktext,0);
+	}
+
+	/**
 	 * Based on the input "TypoLink" TypoScript configuration this will return the generated URL
 	 *
 	 * 	 ' @see typoLink()