Change wording on unsubscribe form to prevent unexpected results
Overview
The Unsubscribe form refers to removing an email address from a Mailing List, when in reality the Contact is removed from the mailing list for all email addresses they may have. For example, if a Contact is subscribed to bulk mail at both Home and Work email addresses and then changes jobs, the inheritor of the Work email account is likely to click the Unsubscribe link, causing the Contact to be unsubscribed at both email addresses. The ideal action is Opt Out, but this is not clear in the language used on the Unsubscribe form, and the general public cannot be expected to parse the distinction between Unsubscribe and Opt Out.
Current behaviour
An inheritor of a Work email account clicks on an unsubscribe link and the Unsubscribe form says "You are requesting to unsubscribe this email address: [email address]" suggesting that only that one address -- not the Contact -- is going to be unsubscribed.
Proposed behaviour
Barring changes to how Mailing Lists/Groups function in the back-end, wording changes to the Unsubscribe form could help clarify for front-end, public users what result their action will take, preventing inadvertent unsubscribes. Such as "You are requesting to unsubscribe all email addresses for {$display_name} from the above mailing list", add a link to the Opt Out form, and other language changes in this commit: https://github.com/philmb/civicrm-core/commit/a82d4d10d1009d25dc0c51c647bf8934391cd77a