Our customer recently switched to Microsoft’s Office 365 exchange service as their email provider. Previously to this transition, this company was hosting their own exchange server. After the upgrade some of the employees would get an error message when emailing within the organization. Here is the message:
So the first thing to try is to delete the autocomplete in Outlook. When you enter the recipient in Outlook , delete the autocomplete suggestion that pops up.
See if that fixes the issue, it didn’t for me .
I then downloaded this NK2View tool from here. I ran this cool little utility and it brought up the autocomplete cache. I scrolled down to the email recipient my customer was having trouble emailing and deleted that entry. I then tried sending a test email and it worked like a charm.
Resolution: When I used the NK2View utility to delete the entry it actually deleted the autocomplete entry for real. Apparently, when they were trying to email within the organization the autocomplete had saved some information about their previous email servers and was trying to deliver the message to the old server. I just deleted the autocomplete entry and everything was fine.
This was posted by techspeeder.