The error is occurring because of the attachment format. It must be a PDF file format, not HTML, RTF, Fast Report.

For Example: Emailing a payslip.

• Click on a wages transaction to highlight
• Click on the Print Pay Slip button
• Click on the email icon
• In the Send by E-mail window, select PDF file Format
• Click OK button

• Tick the Embedded fonts box
• Click OK to continue
  

• In the Files Attached box there should be an attachment
• Click on the Send button to email