Thank you for the post.
Is this the 32-bit or 64-bit version of Outlook 2010?
We are aware of an issue with FileMaker Pro 13.0v9 and the 64-bit version of Outlook.
This is the 32-bit version of Outlook 2010 -- see attached screen shot.
For More Information see: Send Mail using Outlook 2010 Error
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
Here is a link for a free demo download of the Outlook SendMail Plug-In from PCI if you would like to give it a try: http://www.productivecomputing.com/outlook-sendmail
The Outlook SendMail plug-in allows FileMaker® Pro to send plain text or HTML formatted e-mail with multiple attachments through Microsoft® Outlook while suppressing the Outlook security dialog. By using the plug-in you can send better looking e-mail campaigns faster and with less frustration.