This is part of a bigger problem, but...
Emails sent from "https://something--poc--c.cs17.visual.force.com/email/author/emailauthor.jsp" will NOT send.
However, emails from " https://something--poc.cs17.my.salesforce.com/_ui/core/email/author/EmailAuthor" WILL send.
I'm using Conga composer. I really need help getting the first link to work. Ideas?