You may receive NDR something similar to below when sending emails from your Outlook 2007/2010. 'This email address is being protected from spambots. You need JavaScript enabled to view it.' (MAILTO:This email address is being protected from spambots. You need JavaScript enabled to view it.) IMCEAMAILTO-xxx%2B40xxx%This email address is being protected from spambots. You need JavaScript enabled to view it.> A problem occurred and this message couldn't be delivered. Check to be sure the e-mail address is correct. If the problem continues, please contact your helpdesk. Diagnostic information for administrators: Generating server: ExHub.ed.local This email address is being protected from spambots. You need JavaScript enabled to view it. #550 5.4.4 ROUTING.NoConnectorForAddressType; unable to route for address type ## If you give a close look, you can see mailto parameter in those emails are creating issues. When we type an email address inside the square brackets after the Mailto: header, the email address is displayed as an incorrect hyperlink which causes the NDR to generate. Microsoft has released hotfix for this issue and is available to download here, Office 2010 - http://support.microsoft.com/kb/2597052 Office 2007 - http://support.microsoft.com/kb/2475888 -Praveen