Harden array for loops using forEach. Fix "dirty" todo.

The post_data array for loop in email.js failed on me with an object type-error because it didn't do the hasOwnProperty check.   I've converted it and the similar loops in sendgrid.js to Array.forEach().  I also solved that "feels dirty" todo while at it that eliminated the redundant if().  Passes all tests for me. Please merge.  Thanks!