->setFrom($mailFrom)
You can use this to overwrite %mailer_user% in "FROM" field, however email will still be send from %mailer_user%. This field should be used only to add name of the sender, not to change his email address.
If You still want to change shown email You can try, but You can have problems on many servers (for example GMAIL is blocking that option: How to set 'FROM' property using Swiftmailer with Gmail? ).