Sending emails "From" your email address was an issue in the past when the domain had the DMARC security setting enabled.
We would earlier default to sending emails "From" our email - which can now be modified your own custom email server details.
Setting up an SMTP service also sets up the "From" email address for all the email templates in all the jobs. So now we've also made it easier to setup one emails address for the "From" and "Reply-To" fields for the emails being sent via email templates for all jobs.