Changing your From Name and From Email Address in Send Settings
The From Name is the name that appears in your subscribers’ inboxes as who the newsletter is coming from, while the From Email Address is the email address the newsletter is sent from.
The default From Email Address is thiswas@sentwithrasa.io.
You can update the From Name on the Preview page, under Send Settings, to the name of your choosing.
To change the From Email Address to an address that you manage, you must first authenticate your domain. We highly recommend sending from an email address that your contacts are familiar with—this helps reduce the chances of your newsletter landing in spam folders and increases the likelihood that it reaches your subscribers’ inboxes.
Note: We are not able to send from personal email accounts such as gmail.com, yahoo.com, and similar providers.

For example, above the From Name is 'Pushing Send' while the From Email Address is info@pushingsend.rasa.io.