You can require that a visitor to a gallery enters their email address before being allowed to view that gallery. This allows you to know who is viewing your galleries and also gives you an opportunity to communicate with them (i.e. let them know when the gallery is about to expire, to encourage sales, etc.).
To turn on the the email requirement, enable the "Require Email" toggle in the "Settings" panel while editing a gallery.
How to see who's viewed a gallery
When a gallery requires an email address to enter, you can view a list of everyone who has visited the gallery. Go to the Edit Gallery page, and you'll see the "X Emails" button next to the "Require Email" toggle, which indicates that the gallery has X number of guests who have viewed the gallery.
Click the "X Emails" button to view more details.
How to manually add guests to the guest list for a gallery
While in the "Guests" modal (click the "X Emails" button while editing a gallery), you can manually add an email to the guest list for the gallery.
How to email all guests who signed up to view a gallery
You can send an email to all guests who viewed a gallery by clicking the "X Emails" button while editing a gallery, and then click the "Send Email" button.
This will open up the "Compose Email" modal and automatically populate the "To" field with the list of emails, and you can type your email to all the guests.
Note: You can also export the list of emails as a CSV to import into any email marketing platform.