Revert "Fix: Remove sender check, it seems to be bugging."

This reverts commit f051ca8355989a7811f8bf3d1424a42a20b410ba.
Revert "Fix: Corrected check for sender, we should check that it is NULL, not reversed."

This reverts commit 5a42cf8c25307b72723bc3ae23c2ed243fa3ffbd.
Revert "Fix: Corrected check to see if sender exists in header array."

This reverts commit 4cbef1abba29be116c5a65f3c2f72543bcb9f625.
Revert "Fix: Corrected return for setSender() method."

This reverts commit f0ddb654c8bf5e2a8df229a7fd3015ee5772fadf.
Revert "Fix: Corrected function usage."

This reverts commit 27f797622068bfee796a6b87860f78da2ca48684.
Revert "Fix: Set subject regardless."

This reverts commit e3d6ff9b03fbe7e592a15560f439c9f83d27dcc3.
Revert "Fix: Updated PHPDoc to be correct."

This reverts commit c8748a0ea9bec4e5913791cdff3fd84960004a4c.
Revert "Change: Use SMTP mailing rather than PHP mail()."

This reverts commit 9fda241c220cbd1759bf17e77e5842cff0eea845.