Sending a message fails, returning a MIME conversion error message
If you receive the following error message when trying to send a message from Outlook, it might mean that Google Apps Sync's message conversion process is corrupted and needs to be repaired:
This email message was not sent because we were unable to convert the message into Internet format (MIME). Removing attachments or removing forwarded text from the message may enable you to send the message.
Rebooting your computer might fix the problem (so you should try this first). If the problem persists, you'll have to reinstall Google Apps Sync and Outlook from scratch. When doing this, you won't lose any of your mail, contacts, calendar events, notes, or tasks. However, you will have to set up your Outlook specific options.