- Campaigns now have a `type` property (regular, opt-in)
- Opt-in campaigns work for double opt-in lists and e-mail
subscribers who haven't confirmed their subscriptions.
- Lists UI shows a 'Send opt-in campaign' optin that
automatically creates an opt-in campaign for the list
with a default message body that can be tweaked before
sending the campaign.
- Primary usecase is to send opt-in campaigns to subscribers
who are added via bulk import.
This is a breaking change. Adds a new Postgres enum type
`campaign_type` and a new column `type` to the campaigns table.
Kailash Nadh