Because of the way theCloud isolates other users within Exchange 2010 you may find when you are emailing users from other organisations that use theCloud Hosted Exchange that Outlook 2010 displays the error message:
This e-mail message cannot be delivered to <email address> because the e-mail address is no longer valid.
This error can be safely ignored as your email will be delivered successfully but if you would like to disable this warning for peace of mind do the following:
- Select the File tab in Outlook 2010 and select the Options link from the left hand list.
- Select the mail section from the resulting "Outlook Options" window that opens.
- Scroll down this section to the MailTips section (toward the bottom) and click the MailTips Options... button.
- On the resulting "MailTips Options" window under the "Undeliverable Message MailTips" section you will see the option "Recipient address is not valid". Untick this option and then click OK.
- Click OK on the "Outlook Options" window.
You should now be back in Outlook 2010 and will no longer see the e-mail message warning.
NOTE: This only relates to Outlook 2010 and possibly future versions. Previous versions of Outlook do not display this error.