It appears that by default, when requesting validation to get a certificate the app uses the PHP mail() function. Since there is no prompt for setting up a "From:" e-mail address, mail() sends from the following address in my case, www-data@caserver. This is a bad e-mail address and is refused by our mail servers. My quick fix was to modify the ./modules/apply/enterKey.php code to add arguments 4 and 5 to the mail() function to include a "From:" header and a '-fmail@xxx.com' parameter.