Short answer: Double Opt-in requires new subscribers to confirm their email address by clicking a link in an automated confirmation email before they are added to your Mailchimp Audience. Enable it in Mailchimp under Audience > Manage Audience > Settings > Form Settings. Chimpmatic automatically respects this setting — if Double Opt-in is on in Mailchimp, every Contact Form 7 submission triggers the confirmation email. The Pro version lets you override this per form.
Last updated: February 2026
What Is Double Opt-in (and Why Use It)?
Double Opt-in (DOI) is a two-step subscription process that verifies every email address before it enters your Mailchimp Audience:
- Step 1 — Signup: A visitor fills out your Contact Form 7 form on WordPress and submits it. Chimpmatic sends the subscriber data to the Mailchimp API.
- Step 2 — Confirmation: Instead of being added immediately, the subscriber receives an automated email from Mailchimp with a confirmation link. They click the link, and only then are they added to your Audience as a subscribed contact.
Until the subscriber clicks that link, they appear in your Audience with a “Pending” status. They are not counted as active subscribers and will not receive your campaigns.
Why Use Double Opt-in?
- Validates email addresses. Every address on your list belongs to a real person who actively confirmed they want to receive your emails. Typos, fake addresses, and bot submissions are filtered out automatically.
- Protects sender reputation. ISPs like Gmail, Outlook, and Yahoo track engagement metrics. A list of confirmed subscribers signals that your emails are wanted, which improves inbox placement and keeps you out of the spam folder.
- Improves open and click rates. Because every subscriber chose to be there, engagement metrics are naturally higher than a Single Opt-in list that includes unverified addresses.
- Reduces abuse complaints. Subscribers who confirmed their signup are far less likely to mark your emails as spam.
- Creates an audit trail for compliance. You have two records: the form submission timestamp and the confirmation click timestamp. This is the strongest proof of consent for GDPR and other privacy regulations.
Single Opt-in vs. Double Opt-in
Mailchimp uses Single Opt-in by default for most accounts. If your primary contact address is in the EU, some Audiences may default to Double Opt-in. Here is how they compare:
| Factor | Single Opt-in | Double Opt-in |
|---|---|---|
| How it works | Subscriber is added immediately after form submission | Subscriber must click a confirmation link in an email first |
| List growth speed | Faster — no extra step | Slower — some subscribers never confirm (10-30% drop-off) |
| List quality | Lower — includes typos, bots, and fake addresses | Higher — every address is verified and confirmed |
| Open / click rates | Typically lower | Typically higher (confirmed, engaged subscribers) |
| Abuse complaints | Higher risk | Lower risk |
| Sender reputation | More vulnerable to bounces and spam reports | Stronger — ISPs see a clean, engaged list |
| GDPR compliance | Acceptable with documented proof of consent | Gold standard — double proof of intent |
| CAN-SPAM / CCPA | Compliant (requires unsubscribe mechanism) | Compliant with stronger consent evidence |
| Best for | High-volume lead generation, paid ads, instant downloads | Newsletters, long-term lists, EU audiences, compliance-first |
Bottom line: If list quality and deliverability matter more than raw growth speed, use Double Opt-in. If you are running paid campaigns where every conversion counts and you already filter bots with reCAPTCHA, Single Opt-in with good list hygiene can work.
How to Enable Double Opt-in in Mailchimp
This setting lives inside your Mailchimp Audience configuration. You must enable it in Mailchimp before anything changes on the WordPress side — Chimpmatic reads your Audience settings via the API and automatically respects whatever opt-in mode is active.
For an Existing Audience
- Log in to Mailchimp.
- Click Audience in the left menu, then Audience dashboard.
- If you have multiple Audiences, select the correct one from the dropdown.
- Click Manage Audience > Settings.
- Scroll to the Form Settings section and click Edit.
- Select Double Opt-in (or check the box to enable it, depending on your account version).
- Click Save opt-in setting.
Once saved, any new subscriber added through the API (including Chimpmatic submissions) will automatically receive the confirmation email instead of being added immediately.
For a New Audience
When creating a new Audience, check the box labeled “Enable double opt-in” during the setup wizard. This sets the default for all signup forms and API integrations connected to that Audience.
Note: Enabling Double Opt-in also automatically activates reCAPTCHA on your Mailchimp-hosted signup forms.
Managing Opt-in Settings in WordPress with Chimpmatic
Chimpmatic acts as a bridge between Contact Form 7 and the Mailchimp API. It does not have its own separate opt-in toggle in the Lite version — it reads your Audience settings and obeys them.
How It Works with Chimpmatic Lite (Free)
- If Double Opt-in is enabled in Mailchimp → Chimpmatic sends subscribers with
status: pending→ Mailchimp sends the confirmation email → subscriber must click to become active. - If Double Opt-in is disabled in Mailchimp → Chimpmatic sends subscribers with
status: subscribed→ they are added immediately.
You do not need to configure anything in the Chimpmatic Lite tab beyond the standard API key, Audience, and field mapping setup.
The “Pending” Subscriber Issue
This is the most common support question: “My form is working, but I don’t see the subscriber in Mailchimp!”
If Double Opt-in is enabled, the subscriber exists in your Audience but with a “Pending” status. They will not appear in your main subscriber list until they click the confirmation link in their email. To verify:
- Go to Audience > All contacts in Mailchimp.
- Click Manage contacts > View non-subscribed contacts (or filter by status).
- Look for the email address — it should appear as “Pending.”
If the subscriber never confirms, they stay pending. Common reasons: the confirmation email landed in spam, the subscriber forgot, or they mistyped their email address (in which case the confirmation went to the wrong inbox).
For more troubleshooting, see Contact Form 7 Not Sending to Mailchimp? 7 Common Fixes.
Customizing the Confirmation Email
The confirmation email is the first thing a new subscriber sees from you. The default Mailchimp template is functional but generic — customizing it improves recognition and click-through rates.
- In Mailchimp, go to Audience > Signup forms > Form builder.
- Select “Opt-in confirmation email” from the dropdown at the top.
- Customize the following elements:
- Subject line: Replace the default with something specific (e.g., “Confirm your subscription to [Your Brand]” or “One last step to get your free guide”).
- Logo and branding: Add your logo so the email looks official, not like spam.
- Body text: Explain what they signed up for and what to expect.
- Confirmation button text: Change from “Confirm Subscription” to something more engaging (e.g., “Yes, I want in!”).
- Click Save.
You can also customize the Confirmation “Thank You” page and the optional Final Welcome Email (disabled by default) in the same Form builder dropdown. A well-designed sequence — confirmation email → thank you page → welcome email — creates a professional first impression.
Should You Enable the Final Welcome Email?
Mailchimp offers an optional “Final Welcome Email” that sends automatically after the subscriber confirms. It is disabled by default. Enable it when:
- You want to deliver a lead magnet, coupon code, or onboarding link immediately after confirmation.
- You want to set expectations (e.g., “You will receive our newsletter every Tuesday”).
- You have a long delay before your first campaign and want to keep engagement warm.
Leave it disabled if you already have a Customer Journey or Classic Automation that triggers on “Subscribes to audience” — enabling both would send duplicate messages.
When to Use Single Opt-in Instead
Double Opt-in is not always the right choice. Consider Single Opt-in when:
- You prioritize growth speed over list purity. If you are running paid ad campaigns and paying per click, losing 10-30% of signups to confirmation drop-off is a real cost. Every lead that fails to confirm is wasted ad spend.
- You deliver content immediately. If the signup is for an instant download (ebook, checklist, template) and the delivery mechanism is the “Thank You” page or an immediate email, requiring a confirmation click first creates a frustrating user experience.
- You already filter bots with reCAPTCHA. If your CF7 forms use Google reCAPTCHA v3, Cloudflare Turnstile, or similar bot protection, you are already filtering out most fake submissions. Double Opt-in as a spam filter becomes less necessary.
- Your audience is non-EU and your compliance requirements are met. CAN-SPAM requires an unsubscribe mechanism but does not mandate Double Opt-in. If you are US-only and have clear consent language on your form, Single Opt-in is legally compliant.
Advanced: Per-Form Opt-in Override (Chimpmatic Pro)
Sometimes you need both strategies on the same site. For example: Double Opt-in for your newsletter form (clean list, long-term engagement) but Single Opt-in for a webinar registration form (the attendee needs the link immediately).
Chimpmatic Pro lets you override the Mailchimp Audience default on a per-form basis:
- Open your CF7 form in WordPress.
- Go to the ChimpMatic Pro tab.
- Find the Opt-in Settings section.
- Select “Force Single Opt-in” to bypass the Audience default for this form only.
- Save the form.
This gives you the best of both worlds: strict Double Opt-in for general forms that feed your main newsletter, and immediate Single Opt-in for high-intent landing pages where speed matters.
Need Per-Form Opt-in Control?
| Feature | Lite (Free) | Pro |
|---|---|---|
| Respects Mailchimp DOI setting | Yes | Yes |
| Per-form opt-in override | — | Yes |
| Mailchimp Tags | — | Yes |
| Mailchimp Groups | — | Yes |
| GDPR Consent Mapping | — | Yes |
| Advanced Field Mapping | — | Yes |
GDPR and Legal Considerations
For businesses serving EU customers, Double Opt-in is not just a best practice — it is often the safest path to compliance. The General Data Protection Regulation (GDPR) mandates explicit, verifiable consent before sending marketing emails.
Why Double Opt-in Is the GDPR Gold Standard
Double Opt-in provides two verifiable records of consent:
- Form submission timestamp — when the subscriber entered their email address and clicked submit.
- Confirmation click timestamp — when the subscriber actively clicked the confirmation link in the email.
Together, these create an airtight audit trail. If a subscriber or regulator ever questions whether consent was given, you can point to both records as proof of informed, deliberate intent.
Other Privacy Laws
- CAN-SPAM (US): Does not require Double Opt-in, but does require an unsubscribe mechanism and truthful sender information. Single Opt-in is compliant as long as you meet these requirements.
- CASL (Canada): Requires express consent for commercial emails. Double Opt-in provides clear evidence of express consent.
- CCPA (California): Focuses on data rights rather than email consent, but the trend toward stronger privacy protections means implementing DOI now future-proofs your strategy.
Even if you are not legally required to use Double Opt-in, the deliverability and list quality benefits make it worth considering for any serious email marketing program.
While Double Opt-in proves that a subscriber confirmed their address, GDPR also requires you to map consent checkboxes correctly so Mailchimp records what the subscriber consented to. For the full setup, see CF7 GDPR Consent Mapping Guide — that guide completes the compliance loop that Double Opt-in starts.
Troubleshooting Double Opt-in Issues
| Problem | Cause | Fix |
|---|---|---|
| Subscriber stuck as “Pending” | They have not clicked the confirmation link | Check spam folder; resend confirmation; verify email address |
| Confirmation email never arrives | Email landed in spam or was blocked | Whitelist Mailchimp sending domain; check spam filters |
| Subscribers added immediately despite DOI | DOI not enabled for this Audience | Check Audience > Settings > Form Settings |
| Want DOI on some forms but not others | Mailchimp DOI is a global Audience setting | Use Chimpmatic Pro per-form override |
| Confirmation email looks generic | Default template not customized | Customize in Signup forms > Form builder |
1. Subscriber Stuck as “Pending”
This is the expected behavior with Double Opt-in — the subscriber has not clicked the confirmation link yet. Check with the subscriber to see if the email landed in their spam or promotions folder. In Mailchimp, you can view pending contacts under Audience > All contacts by filtering for non-subscribed contacts. If the subscriber never confirms, they will remain pending indefinitely.
2. Confirmation Email Never Arrives
If the subscriber says they never received the confirmation email, the most common causes are:
- The email landed in their spam or junk folder.
- Their email provider blocked the message (common with strict corporate email filters).
- They mistyped their email address on the form, so the confirmation went to the wrong inbox.
To troubleshoot: check the subscriber’s email address in Mailchimp for typos, ask them to whitelist Mailchimp’s sending domain, and if needed, follow the resend process below.
How to Resend the Confirmation Email
Mailchimp does not have a “resend confirmation” button. To trigger a fresh confirmation email for a pending subscriber:
- Go to Audience > All contacts and filter for non-subscribed/pending contacts.
- Find the subscriber and delete them from the Audience (this removes the pending record).
- Ask the subscriber to re-submit the form on your website.
- Chimpmatic will send the data to the API again, and Mailchimp will send a new confirmation email.
Before deleting, verify the email address is correct. If the subscriber mistyped their address, they will never receive the confirmation regardless of how many times it is sent.
3. Subscribers Added Immediately Despite DOI Being On
If subscribers are being added as “Subscribed” instead of “Pending,” Double Opt-in may not actually be enabled for this Audience. Go to Audience > Manage Audience > Settings > Form Settings > Edit and verify the opt-in setting. Also check whether a Chimpmatic Pro per-form override is forcing Single Opt-in on a specific form.
4. Want Double Opt-in on Some Forms but Not Others
Mailchimp’s Double Opt-in setting applies to the entire Audience — there is no way to set it per-form inside Mailchimp itself. The Chimpmatic Pro per-form override solves this by letting you force Single Opt-in on specific forms while keeping the Audience default as Double Opt-in.
5. Confirmation Email Looks Generic or Spammy
The default Mailchimp confirmation email is plain and unbranded. Subscribers may not recognize it and ignore or delete it. Go to Audience > Signup forms > Form builder, select “Opt-in confirmation email” from the dropdown, and customize the subject line, logo, body text, and button text. A branded, clear confirmation email significantly improves click-through rates.
Frequently Asked Questions
What is Double Opt-in in Mailchimp?
Double Opt-in is a two-step process where new subscribers must confirm their email address by clicking a link in a confirmation email before being added to your Mailchimp Audience. Until they confirm, they appear as “Pending” and do not receive campaigns.
How do I enable Double Opt-in in Mailchimp?
Go to Audience > Manage Audience > Settings > Form Settings > Edit, then select Double Opt-in and click “Save opt-in setting.” For new Audiences, check the “Enable double opt-in” box during creation.
Does Chimpmatic support Double Opt-in?
Yes. Chimpmatic Lite automatically respects your Mailchimp Audience setting. If Double Opt-in is enabled in Mailchimp, Chimpmatic sends subscribers with “pending” status, which triggers the confirmation email. Chimpmatic Pro adds per-form override to force Single or Double Opt-in on specific forms.
Why is my subscriber showing as “Pending” in Mailchimp?
Because Double Opt-in is enabled and the subscriber has not clicked the confirmation link in their email yet. Check if the email landed in their spam folder or if they mistyped their address. They will remain “Pending” until they confirm.
Can I use Double Opt-in on some forms and Single on others?
Not with Mailchimp alone — the opt-in setting is per-Audience, not per-form. However, Chimpmatic Pro lets you override the Audience default on each CF7 form individually.
Is Double Opt-in required by GDPR?
GDPR requires “explicit, verifiable consent” but does not specifically mandate Double Opt-in. However, DOI is widely considered the gold standard for EU audiences because it provides two timestamps of consent (form submission and confirmation click), creating the strongest possible audit trail. It is commonly used as a best practice for compliance, though your specific legal obligations depend on your jurisdiction and use case.
Does Double Opt-in hurt my list growth?
Yes, it reduces signups by roughly 10-30% because some subscribers never click the confirmation link. However, the subscribers who do confirm are higher quality — they are more engaged, less likely to report spam, and generate better deliverability metrics. The trade-off is a smaller but more valuable list.
How do I customize the Mailchimp confirmation email?
Go to Audience > Signup forms > Form builder, then select “Opt-in confirmation email” from the dropdown. You can customize the subject line, add your logo, change the body text, and modify the confirmation button. You can also customize the “Thank You” page and enable a Final Welcome Email in the same dropdown.
What happens if a subscriber never confirms?
They stay in your Audience with a “Pending” status indefinitely. They will not receive campaigns and do not count toward your active subscriber billing. You can delete pending contacts periodically to keep your Audience clean.
Why are my Contact Form 7 subscribers showing as “Pending” in Mailchimp?
Because Double Opt-in is enabled on your Mailchimp Audience. When Chimpmatic sends a subscriber via the API with DOI active, Mailchimp sets their status to “Pending” and sends a confirmation email. The subscriber must click the confirmation link before they become active. This is not a bug — it is the expected behavior. Check your Audience settings if you want to switch to Single Opt-in, or use Chimpmatic Pro to override it on specific forms.
Does Single Opt-in comply with CAN-SPAM?
Yes. CAN-SPAM requires an unsubscribe mechanism and truthful sender information but does not mandate Double Opt-in. Single Opt-in is fully compliant in the US as long as you include an unsubscribe link in every email.
Where can I find Mailchimp’s official Double Opt-in documentation?
Mailchimp maintains several help articles on this topic: About Double Opt-in, Single vs. Double Opt-in, and Choose Opt-in Settings. These cover the Mailchimp side. For the WordPress + CF7 integration side, you are in the right place.
Next Steps
- New to Chimpmatic? Start with the CF7 to Mailchimp setup guide.
- Need GDPR consent mapping? Read Collect consent with GDPR.
- Subscribers not appearing? See CF7 Not Sending to Mailchimp? 7 Common Fixes.
- Need per-form control? Upgrade to Pro for per-form opt-in override.
- Still have questions? Get in touch — we are happy to help.