Hello,
I faced with situation when in Mailchimp form settings was enabled for double opt-in, and when we add new subscription from Drupal integrated form after submit there is no confirmation mail sent from Mailchimp service.
I debugged the process and I got result from Mailchimp after calling addOrUpdateMember with status for contact as 'pending' and still no confirmation.
Note
Opt-in settings only apply to Mailchimp signup forms, so form integrations and API opt-in are unaffected.
Mailchimp official documentatin: https://mailchimp.com/help/set-signup-preferences/
Should I receive a confirmation if contact was added via API?
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
Perhaps 🐛 Already subscribed member gets status "pending" when he/she subscribes using double opt-in, but gets no confirmation mail Needs review (which I just created) is related to this issue?
Only in that issue I report that no confirmation mail is sent when trying to subscribe an existing mail address. This looks to be about no confirmation mail being send for a new subscriber.