-- This is regarding GoDaddy hosting only. The Postman SMTP plugin is brilliant and the Easy WP SMTP plugin with work with the majority of hosting companies.
Jason, NO, you didn't really fix anything. You are simply making it look like you did by duplicating what is happening automatically on the hosting server. Your plugin (or any SMTP plugin on a GoDaddy site) is not actually doing anything in this particular case.
Using an SMTP plugin for GoDaddy WordPress hosting is a completely useless extra step. GoDaddy will automatically route all PHP mail() email through their proxy controlled relay servers no matter what you attempt to do with scripts or plugins. Email from a GoDaddy hosted site can only be delivered to GoDaddy hosted forwarders or email accounts.
Even in this particular case where it looks like the plugin is doing the job, the efforts of the plugin are completely ignored on the server.
Per GoDaddy server admin staff; their antispam measures are hardcoded into the servers so that wp_mail() will always use PHP mail() and PHP mail() will always send mail through their relay servers. Any email is automatically whitelisted when sent from any of their website hosting accounts to GoDaddy hosted email accounts. Don't ignore the SPF record though, that should always be setup to ensure normal email delivery.
No need to argue, just try using the plugin to send email directly to a Gmail account or any mailbox not hosted by GoDaddy. It will fail.
THIS IS VERY SIMPLE.
You absolutely cannot get around GoDaddy's antispam security measures. You don't need to install anything if, like @andrethierry, your website & email are hosted by GoDaddy. Just make sure your WordPress site owner email address and your contact forms send mail TO a GoDaddy hosted forwarder or email account. Andre was just working too hard (just like many of us have) to solve a expected problem when GoDaddy already had a super simple solution hardcoded into the server.