Handle subscriptions better

[sterndata]

People often complain about receiving mail from the forums. This could be improved with either or both of these:

1. Add an explicit unsubscribe link to emails from forum-level subscriptions. Currently, the link simply takes you to the forum.

2. For subscriptions to forums (not individual topics), require confirmation either via on-site dialog or replying to a "Please confirm your subscription to the XXX forum" link in the email.

[dd32]

Add an explicit unsubscribe link to emails from forum-level subscriptions. Currently, the link simply takes you to the forum.

This is currently blocked upstream by ​#bbpress3229 as each email that is sent actually goes to up-to 100 people. (also ​#bbpress2707 is this ticket effectively)

For subscriptions to forums (not individual topics), require confirmation either via on-site dialog or replying to a "Please confirm your subscription to the XXX forum" link in the email.

Adding a JS-based dialogue "Are you sure you want to subscribe by emails to all new topics in the XXXXXXX forum?" is something that has been in the back of my mind for a while, and I'm definitely for that.
Does anyone have any wording suggestion that's concise and to the point? The above text might actually do..

[dd32]

Just noting that forum-wide subscriptions were disabled.

[dd32]

In 11562:

Support Forums: 'unroll' forum subscription emails, sending an individual email per recipient rather than BCC'ing them all together.

See #5505.

[dd32]

In 11563:

Support Forums: Fix a logic order reversal in [11562] (Didn't affect email notifications), avoid some PHP Notices.

See #5505.

[dd32]

In 11580:

Support Forums: Add unsubscription links to plugin/theme/tag subscription emails.

Note: This does not add unsubscription links to bbPress emails, only the ones this plugin adds.
Emails from bbPress for forum / topic subscription ('notify me of replies') will not have these links.

See #5505, #3456.