Knowledge Base/E-Mail Support Forum
Microsoft Outlook 2010 - IMCEAMAILTO issue causing "Delivery has failed ..." Bounced Email
Carl Gren
posted this on November 10, 2011 04:25 pm
In Outlook 2010, when a user replies to some emails, the 'E-mail Type:' changes from the expected SMTP to MAILTO.
When the user sends the email it is rejected because Outlook or Exchange is adding @domain.local to the end of the recipient's email address.
In addition, when you click a 'mailto: link' on a web-page or hyperlink to send an e-mail, the same problem occurs and the incorrectly formatted address is automatically stored in the Outlook auto-complete list. So even when you type the offending addresses later again manually, they will be "auto-corrected" by Outlook into the wrong formatted address (the address that originally used 'mailto' incorrectly) and the e-mail will fail.
Microsoft Support has confirmed that this is a recently identified and known bug in Outlook 2010 caused by a recent security update and that they are working on a hot fix for it. Unfortunately the hot fix software patch will not be available until end of 2011.
Work Around
Until the hotfix is released, a good work around fix is to delete the auto-complete entry manually. This can be performed by downloading and using the NK2Edit tool from Nirsoft. Below is a link to a great walk through on using the tool as well as a download link for the tool.