Login as Joomla administrator, select Extensions - Module Manager - and then select the Simple Email Form module you installed.

Under Advanced Options you will need to configure these three fields:

Select Yes for the first option.
Leave the 2nd field blank to allow any file types to be uploaded. 
Otherwise, enter allowed extensions separated by commas.
To allow only graphics, for example, enter:
The last field must have the absolute path as specified by your
web hosting provider to the folder you create to store file uploads.
Enable Test Mode to test and observe any error messages.
Make sure the Joomla user has rights to write to this directory.

If your attachments are not showing up:

  • You have not configured the right path
  • You do not have write rights (permissions) to the target directory
  • You are trying to upload a file which is not allowed