Mailbag Contact Form

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When a WordPress form’s Mailchimp integration stops working

When signups stop reaching Mailchimp, it's usually one of four things: the API key was revoked or regenerated, the audience was deleted or renamed in a way the form still refers to, Mailchimp is refusing specific addresses, or the plugin's code no longer matches what Mailchimp expects. The hard part is that most form plugins don't tell you — you find out when the list stops growing.

Tell the causes apart

  • Nothing arrives at all — the key or the audience. Mailchimp answers every call with “unauthorised” or “resource not found”.
  • Some arrive, some don't — Mailchimp is refusing particular addresses: invalid, previously unsubscribed, or flagged for compliance. That's correct behaviour, and retrying won't change it.
  • It stopped after an update — of the plugin, WordPress or PHP. Check the plugin's changelog and support forum.

Getting the missed signups back

Only possible if they were saved somewhere. A form that sends straight to Mailchimp without keeping a copy has lost them. If your form plugin stores entries, export the period to CSV and import it into Mailchimp — carefully, only with people who gave consent.

How Mailbag Pro prevents the silent part

With the free Mailbag Contact Form, every entry is saved in WordPress first. Mailbag Pro, the paid add-on, then watches each connection:

  • When Mailchimp starts refusing calls, the connection is marked failing and you get an alert email — at most once a day per connection, sent to an address you choose, typically the agency's rather than the client's.
  • Entries that couldn't be delivered wait in a queue with Mailchimp's own reason. They're retried on a schedule for up to 7 days, and sent as soon as the connection works.
  • When it's fixed, you get one working again email with how many entries were delivered from the queue.
  • Addresses Mailchimp permanently refuses are shown on each entry, not retried, and don't mark the whole connection as broken.

See Mailbag Pro.

This is Mailbag Pro, the paid add-on to the free Mailbag Contact Form plugin. See what it costs, and what happens if you ever stop paying.

Mailbag Pro and pricing