What you control. Set in Tacey, per store.
These are the settings on this tool's page in Tacey, in the words the app uses. Where a setting has a default, it is stated.
Let customers change the email / the phone numberEach is its own switch, and both are on by default.
Let customers change their nameChanges the name on the order's shipping address. Off by default. A blank name is never allowed.
Let customers remove their email or phone entirelyOff by default. A blank field is treated as a mistake, never as a request to delete it.
Only allow a phone number from the shipping countryOn by default. Turn it off to let customers pick any country.
Refuse known disposable email addressesOff by default. Only domains on Tacey's own list are refused, so an address Tacey does not recognise is always allowed.
Also update the customer's accountOff by default. When on, a change also updates the customer's Shopify account, including the email they sign in with, but only when the customer is signed in to that account. A change from an order link without signing in updates the order only.
Email the old address when the email changesOn by default. A short notice from your store to the previous address.
Email me when a customer changes their contact detailsOff by default. Needs a contact email set for your store.