InfoPath Dev

 We have a form for a request that has an attachment option.  Unfortunately, a lot of the names that are being used to name files contain special characters.  So when the file is attached, we receive an error on submission, however the form still submits.  I am looking for suggestions to stop the form from being submitted if there is a problem with the attachment.  Thanks.

You could set a rule on the file attachment that removes the special characters using the translate xpath function.

The rule would set the value of the field equal to translate(field, '&','') - where the ampersand is a special character and the double quote at the end is actually to single quotes.