Sending emails using an alias or reply-to address

When sending an email message from a valid gmail alias, it shows up as being sent from the primary email address. It would be useful to add a reply-to address, which I believe is supported from the API.

Start by locating ezgmail's email-sending entry point and reviewing how it builds Gmail API messages. Confirm how Gmail aliases and reply-to headers are represented, then verify that messages sent through an alias display the alias and support the requested reply-to address.

Written by the indexing model from the issue text.