Sprout Email with Mailchimp

Question

Currently I am using Sprout Email 2.4.7 to send newsletter mailings to mailchimp.

I am trying to prefill email.fromName, email.fromEmail, email.replyTo with default values so these don't need to be entered every time a new mailing is being set up in the Craft 2 cp section.

Setting this in the email template file does not work

{% set email.fromName = 'My Company' %}
{% set email.fromEmail = 'john@doe.com' %}
{% set email.replyTo = 'john@doe.com' %}

Any ideas how this could be done in a clean way?

thanks!