That’s a yes!
When a patron orders tickets online, they must enter their email address, so it does get added to their customer record in Wintix.
If you bring up their record and look at the Phone numbers tab, you will see their email address, but the Opt in to the email list button is UNchecked. That’s where the Include only records that have opted in comes into play when running mailing lists. (See screen shot below.)