OK, so WHY is it that the FROM: section in the external POP account preferences allows you to send mail with a different textual name, but not a different email address? If I send mail from, say, Gmail using a different account, the "from" line that people see is my other account. If you look at the full headers, you can see it was sent through Gmail, but just the normal headers and you see email@example.com.
It is important that my users be able to do that inside Zimbra as well. What up?