Are you meaning to set the “from” using the data of the newsletter creator (or the user which actually press “send”?). We’re refactoring the internal mailer and it will be easy to support the “from” field so we can include even that option or add a official hook to deal with that.
Can you kindly explain me if you stored the user who created the newsletter and used it to change the from?
A newsletter is ready to go, so I press the Next button and see options like to choose mail list and other stuff. I added four fields, the same as on the “Settings->General Settings” – Sender email address, Sender name, Return path, Reply to. The fields are pre-filled with name and email address from my WP-profile. Now, when I send an email, it goes from my name. The plugin.php extracts those details from the email and uses for sender details.
But, what would be really great, if you would add an option where to get prefills from, like a toggle box “Main settings – User profile – Custom”. Or even to choose details of other WP-users or a list of “Senders” with details required.
As for myself, it would add usability. But, of course, other plugin users may want something different.