Email recipient cannot view attachments sent via Outlook.

When sending an email from Atrex via Outlook to a receipient that does not have Outlook, the attachments sent via Atrex may not be received by the end user or they are embedded within the email in a file called winmail.dat. 

The problem is caused by the Transport Neutral Encapsulation Format (TNEF) used by Outlook when sending emails in the rich text format, but the recipients email software (such as Outlook Express) doesn't know how to decode the TNEF format.
To ensure that any attachment is not mistakenly converted by Outlook (i.e., PDF arrives as DAT), there are two options.
The first option is to limit the use of TNEF to your internal mail.  The following are the necessary steps:
1. On the "Tools" menu, click "Options", then click the "Mail Format" tab, and then the "Internet Format" button.
2. Set "When sending Outlook Rich Text messages to Internet ..." to either "Convert to HTML format" or "Convert to Plain Text format".
The second option is to disable TNEF completely.  The following are the necessary steps:
1. On the "Tools" menu, click "Options", and then click the "Mail Format" tab.
2. In the "Send in this message format" list, click "Plain Text" or "HTML", and then click "OK".

If these options do not resolve the issue, you will need to contact Microsoft Support for additional assistance as the issue can only be resolved from within the Outlook software package.