Product Support

MailChimp Integration

Integrates Participants Database with your MailChimp account.

Product Setup

This plugin requires you have an account established with MailChimp before you configure it. Once you have your MailChimp account set up, you’ll need to get an API Key.

Getting Your MailChimp API Key

On your avatar menu (upper right corner while logged in to MailChimp) click on “account.” Once there, under the “extras” menu, select “API Keys.” On that screen, you’re given a way to create an API key. You can have several keys, so even if you have a key, it’s a good idea to create a new one for this purpose. Give it a name so you know where it is being used. Once the key code is generated, copy and paste it into the “API Key” setting in the MailChimp Integration settings menu, found under Participants Database in the WP admin.

Setting Up Your Mailing List

When you click on “Save Changes” the API Key will be used to get your list of mailing lists at MailChimp. You will need to have at least one mailing list established in order to use the plugin because new subscribers have to go to a specific list. In the “Subscription List” dropdown will be your mailing lists at MailChimp. If you don’t see it, click on “Save Changes” to refresh the list.

Select the list you want your Participants Database signups to be subscribed to.

Set Up Your “Opt-In” Checkbox

In most cases, you’ll want to provide a way for your users to opt-in to your mailing list. Do this by creating an opt-in field that consists of a check box with the values “yes,no” You can default it to “yes” if you want it checked to begin with. Once that is set up, you need to tell the plugin which field it is in the List Select Field setting.

If you want to use another language or give the checkbox a different label, you can use the value label format like this: Yes::yes,No::no

As long as the saved values (the second of each :: pair) are “yes” and “no” it will work.

Completing the Setup

Once you have the API Key and mailing list set up, you can make sure the rest of the settings are what you want. Take a look at the “Settings” tab here for more explanation.

Importing Subscribers

When you import records using a CSV file, these will also be synchronized with your MailChimp list. You can use a CSV import to add a bunch of subscribers or update their subscription status over at MailChimp.

If you already have records in your Participants Database and you want to add them all to your MailChimp list, you need to export them, then re-import them (using the record ID as a match field so you won’t end up with duplicates) which will update all of them with your MailChimp list. Be sure the needed fields are configured to be included in the CSV export by having the “CSV” box checked in the field definition.

Note: CSV imports must contain both the “email” and “list select field” data in order for the subscriber to be added or updated at MailChimp.

Two-Way Synchronization

the webhook link…yours will look different.

When a subscriber receives an email you’ve sent using MailChimp, there is an unsubscribe link they can use to be unsubscribed. In order for this to be reflected in your Participants Database record, a communication link between MailChimp and your WordPress site must be established. This is done using a “webhook” which is a secure URL that the MailChimp list can use to communicate to your WP site.

To set up a webhook, first find the webhook URL that you will see at the top of the MailChimp Integration settings page in your WP admin.  Copy that URL. We’re going to use that over at MailChimp, but first you must flush the permalinks to activate the webhook URL. To do this, go to the “permalinks” setting under the Settings item in your WP admin. On the permalinks settings page just click on “Save Changes” and that will flush the permalinks and make sure the webhook URL is set up to receive data from MailChimp.

Now, go to MailChimp and select the list you are using with Participants Database. Go to the settings page for that list and find the “webhooks” setting.

On the webhooks page, click on the “Create New Webhook” button found on the upper right. This will open a form where you can paste the webhook URL you got from the plugin settings. Once that is saved, you will be able to select what type of messages will be sent. Just accept the defaults and save the webhook.

If you get some kind of error message when trying to set up the webhook, make sure you copied in the exact URL given in the plugin settings. Also, flush the permalinks to be sure WP has the URL set up. Errors such as a 500 or 403 indicate possible security rules on your web server designed to block unauthorized access. Talk to your web host about the problem in cases like this. MailChimp also has a support page for webhooks that could be helpful.

Manually Updating Multiple Records

As of version 1.5, it is possible to update multiple records in a single operation. This is done on the “List Participants” page in the Participants Database admin, there are new MailChimp functions in the “With Selected” dropdown.

To update (synchronize with MailChimp) multiple records, selected the records you want updated, then select “Update to MailChimp” and click “Apply.” All your merge fields and subscribe statuses will be updated to MailChimp, so all the subscriber’s info there will match the info in Participants Database.

Mass Subscribe/Unsubscribe

If you need to subscribe or unsubscribe multiple records, you can to that in a similar way.

Product Settings


This is the key code provided by MailChimp that is unique to your MailChimp account.

Subscription List

Once you have entered your API key and saved the settings, you can select which list people will be signed up to when they register.

List Select Field

This is the name of the field used to opt in to your list. Usually, it’s a checkbox where they simply say “yes” to being added to the list.

Use Double Opt-In

This means that when someone signs up and indicates they want to join the list, MailChimp sends them an email where they can confirm that choice. This is a really good idea to avoid trouble such as people getting your newsletter who actually don’t want it, or getting spam email addresses into your list. Please note that in some countries, a double-opt-in is a legal requirement for mass email.

The way this works is new registrations will have a “pending” status when they sign up. When (or if) they confirm the subscription, their status will be changed to “subscribed.”

Note: when using double opt-in, new registrations will not be visible in MailChimp until they confirm their subscription. Before they confirm, they are considered “pending” and will not show up in your lists at MailChimp. You can find those registrations at MailChimp if you search for the email address.

Pending Label

While a registrant has a pending status, this label is used for the value of the List Select Field. You can use this in list searches to find people who have not confirmed their subscription yet.

Merge Fields

This setting uses a special string to define additional fields that will be saved in the MailChimp list. Typically, this is their first and last name, but it can be just about anything. It does have to be a field that is included in the Participants Database form because otherwise there won’t be any value to save to the MailChimp subscriber list. The default value for the setting is:


The way this works is this is actually a map of the Participants Database field to the MailChimp field. The format is pdb_field:MAILCHIMP_FIELD with each field pair separated by commas. This is a simple one-to-one mapping: for instance it’s not possible to combine several Participants Database fields into a single MailChimp field.

The Mismatched Merge Fields Warning

If the list of merge fields you have defined in this setting don’t match the list of merge fields defined at MailChimp, you will get a warning message. You can ignore this if you want, the main functionality will work as expected, and any merge fields that do match will work.

What it means is that, for instance, if you didn’t have a “city” merge field defined here, and you did at MailChimp, the data for the registrant’s city will not be sent to MailChimp. The warning is so you will know why your merge fields are not getting populated with data.


If a user unsubscribes on their profile page, will they be unsubscribed at MailChimp?

Yes, every time a record is updated on your site, that info is passed to MailChimp, so they can unsubscribe in either place, it won’t matter, they stay synchronized.

I'm not getting subscriber updates from MailChimp, how do I get webhooks working?

To troubleshoot webhooks, follow these steps:

  1. Check the “Subscription List” setting in the add-0n settings and make sure you have the correct list selected
  2. Check the webhook URL at the top of the page. Now go to MailChimp and check the webhook for the list (found in the list’s settings page) Make sure they are the same.
  3. Copy the webhook URL and try it in a browser. You should get a “No request details found.” message. If you get a 403, or a 500, check your site security filters or contact your web host with the information.
  4. If you get a 404, refresh the permalinks in the general settings of your WordPress site, then try to open the webhook URL in the browser again.
I have Double Opt-In checked, and I'm getting signups, but they aren't appearing at MailChimp, what's happening?

Having Double Opt-In checked changes how things work in several ways.

If you have “Use Double Opt-In” checked, and someone signs up, their info is sent to MailChimp only if they have the “List Select Field” checked. In both cases, you won’t see them at MailChimp at first.

If they agree to be on the list when they sing up, their info will be sent to MailChimp, but you will not see them in the list there until they confirm the opt-in by email. You can still find them with a search, however. You’ll see their status is “pending.”

If they don’t agree to join the list, their info won’t be sent to MailChimp at all. In this case, if they later update their record to join the list, their info will be sent to MailChimp at that time and they will need to confirm in order to join the list.

Support Discussions for MailChimp Integration

  • I’ve installed the plugin, and double checked that everything is set up correctly, but I’m not getting a new Mailchimp record when I add it to PDB. The webhook is giving the correct response when I test it. What else can I check?

    • If you have “double-opt-in” enabled, the new record won’t show up at MailChimp until the user opts in. You can see the pending subcribers at MailChimp, I forgot exactly how, though.

      • I’ve tried it with that option on, and off, no luck. I looked in my opt-in field for the value ‘pending,’ but there’s nothing there, either.

        • Can we troubleshoot this through whatsapp? I can never tell when you’ve responded unless I stay on this page.

        • I’m not a whatsapp user…make sure you’re subscribed to the thread and you’ll get an email.

        • OK, need to make sure the configuration is correct. On the MailChimp Integration plugin settings, are you getting the “Subscription List” dropdown populated? Do you have your list select field defined? What is the configuration of that field?

        • Yes, here’s what I see:
          List Name ID Subscribers
          RAS Update List 487939a514 406
          Edit this list in Mailchimp
          Merge Fields
          Name Tag Type
          Email Address* EMAIL email
          Address_1 ADD1 text
          Address_2 ADD2 text
          ALCOR (AL) ALCOR text
          City CITY text
          Club_Code CLUB text
          First Name* FNAME text
          Last Name* LNAME text

        • The select field is called opt-in, and it’s a checkbox, default ‘yes.’

        • OK, turn plugin debugging on (Participants Database settings under the advanced tab) then test adding a new record.

        • Log file initiated at: October 25, 2019 9:44 pm UTC
          [10/25/19 9:44pm UTC]
          action: delete
          query: DELETE FROM wp_14_participants_database WHERE id IN ( ‘363’,’361′ )
          [10/25/19 9:44pm UTC]
          list query: SELECT * FROM wp_14_participants_database p WHERE p.db_group LIKE “%Directory%” ORDER BY p.venue_date desc
          [10/25/19 9:45pm UTC]
          Participants_Db::process_form storing record: INSERT INTO wp_14_participants_database SET date_recorded = NOW(), date_updated = NOW(), db_group = ‘Directory’, venue_name = ”, venue_type = ”, venue_date = NULL, host = ”, host_type = ”, group_size = NULL, canceled = ”, first_name = ”, last_name = ”, address = ”, city = ”, state = ”, zip = ”, phone = ”, email = ”, opt_in = ‘No’, photo = ”, website = ”, interests = ”, approved = ‘no’, private_id = ‘CLB0E’, d_last_name = ‘Schmoe’, d_first_name = ‘Joe’, d_email = ‘’, d_status = ‘X’, d_home_phone = ‘8043798175’, d_alcor = ‘4404’, d_address = ‘11536 Smoketree Dr’
          [10/25/19 9:45pm UTC]
          list query: SELECT * FROM wp_14_participants_database p WHERE p.db_group LIKE “%Directory%” ORDER BY p.venue_date desc

        • The opt_in field has a value of “no” so it won’t be added. Try updating the record with the opt in checked, or make a new one with the opt in checked.

        • Tried both, no change. When I try to post the log, I keep getting a message that it’s spam. How can I get the log to you? Can I send you log in info somehow?

        • OK, I’m sorry, I just realized that the plugin debugging log won’t log the data send, this is really only going to show up in the proper php error log.

          Back to your settings….in the MailChimp Integration settings, first check to make certain your API key is correct. You will know it is correct when the “Subscription List” setting below that is populated with the lists you defined at MailChimp. If that dropdown is not populated, then the API key is not correct or not working.

          Of course, make sure you’re checking the correct list at MailChimp. I’m sorry if you’ve done all this, but when things don’t work, the settings are the most likely reason.

          Also, another thought: what kind of hosting are you using? There is an outside chance that the communication is blocked by your server configuration. You will need to check with your hosting provider to delve into that.

        • Try this:

        • Here are some screen shots–do you see anything wrong?

        • I have not tested the effect of using another MailChimp plugin with it, so there may be some unanticipated effects there. I did not realize you were trying to do that. You could try testing it with the other plugin deactivated.

          The Participants Database MailChimp plugin maintains its own list of merge fields, so it will only sync the fields you have defined in the settings for that plugin.

          The settings look good, it looks like you are connected to MailChimp.

        • I deactivated the other plugin, no change. Where is the PDB list of merge fields? The documentation on your plugin page says:
          This should be a comma-separated list of connections between the PDB fieldname and the MailChimp merge field tag name. It is important that the fields listed here match the merge fields configured in your MailChimp list.

        • Is it possible for you to set up your php error log? I am at the end of suggestions I have for why it’s not working for you, and that is a good way to see if there are issues on the php end of things.

          The merge field setting for the PDB MailChimp plugin is a string that maps a PDB field to a MailChimp merge field. For example:


          This setting value maps the PDB field ‘first_name’ to the MailChimp merge field “FNAME” and each comma-separated pair after that defines another mapping with the PDB field on hte left of the colon, and the merge field on the right. The email field is mapped by default, no need to add that one (unless you are using a non-standard email field in PDB), this setting is for the purpose of adding any other merge fields you need.

        • I did find a php error, and I corrected the last name field, so now I get no errors, but I also don’t get a new record in Mailchimp.

          Here’s something else interesting though. Here’s the error before I fixed it. I was trying to add donald duck, and I thought it got added to Mailchimp because the audience count increased by 1 over yesterday. But, it turned out that sackett added himself to Mailchimp last night. Why did his name turn up in this error message?

        • Looks like the name of the field is wrong, should be d_last_name. This will be in your merge fields setting.

        • Right, but I fixed it–reread my last update. No errors now, but no Mailchimp update, either.

        • OK, good. Did you get your php error log set up? That would be the next step here, I don’t have any more suggestions, everything looks good from what I’ve seen.

        • Yes, I have php errors set up, but once I corrected the last name error, I get no errors. I tried adding from the Mailchimp side, and the add works on that side, but nothing happens on the PDB side, and no errors.

          I did notice though, that I can force an error to show up by deliberately coding the merge field wrong on the PDB side, then adding on the Mailchimp side. This is what I get. Do you have any troubleshooting ideas? Can you force an error in your plugin?

  • I have two record formats, one in group Directory. Can I have Mailchimp sync to those records only? I don’t want to touch the non-Directory records.

    If my site is a multisite, can I have a Participant Database for each subdomain, or am I limited to one for the entire multisite?

    • There isn’t any way to selectively prevent syncing to the MailChimp list, however if the record does not have a valid email then it won’t try to update…so if your other record type doesn’t have data in the email field, it won’t be updated.

      On multisite, Participants Database has a separate set of db tables for each site: they are completely separate.

      • That’s not going to work for my database with 2 different record formats, as the fields from the 2 groups are 1 contiguous record, so I’d have to create the fields for the entire record in Mailchimp, right?

        But, since each subdomain has a separate PD, I can create a subdomain just for the Directory records, right? I won’t be able to access the new PD from the existing subdomain, but I don’t care about that.

        The plus to this approach, outside of the Mailchimp capability: if you set up a WP multisite, you can have as many PD’s as you want, one for each subdomain. As long as you don’t need to send data between subdomains.

        • You don’t need to add merge fields to the MailChimp configuration. I guess I don’t understand what you’re trying to do. It sounds like you have two different kinds of record in the same database…do both kinds of record represent a person, but only one type needs to be synced with MailChimp?

          I don’t want to confuse the conversation with issues relating to multisite. Just know that each site on a multisite setup is completely separate, with its own settings.

        • Yes, I have two totally different records, no relation to each other. Venues tracks our events, and Directory is our member database. Since the member db has the email, that’s what we want to sync with Mailchimp. So I have an ID field, then 10 or so Venue fields, followed by 15 or so Directory fields, in a PD group.

          For a Directory record, all the Venue fields are blank, and the ID=D, and for a Venue record, all the Directory fields are blank, ID=blank.

          I want to sync on the Directory fields, but not Venue fields. If I set up a sync, don’t I have to include both Venue and Directory fields in Mailchimp?

        • The only field that you really need fo MailChimp is email, and that is already set up. (First name and Last name are also set up by default) As I mentioned, you don’t need to set up any merge fields in MailChimp.

          There isn’t a way to prevent records from being synced to MailChimp if they have a valid email address, but it probably won’t be a problem because I’m guessing none of your venue records will have opted in to your mailing list.

        • Ok, I’ve got it now. The only required fields are email, first and last names. Merge fields are optional, so I can control what other fields get updated. I thought it would default to all Mailchimp fields. That fits my scenario perfectly.

          The fact that it won’t sync fields with no email is great, because Mailchimp doesn’t allow blank emails, and I can keep those record in my PDB.

          I’m buying the plugin.

  • Must be doing something wrong. Getting ” Please select a mailing list and save the settings before completing the plugin configuration.” warning.

    The mailing list is selected from Mailchimp
    The list select field is also selected.

    Which one is it referring to?

    • Once you set the MailChimp API key and save the settings, the available lists will show up in the “Subscription List” selector. Select your list there, then save the settings. The notice should go away and then you can complete the setup with the other settings.

    • I should also mention… It’s working, so I can ignore the warning…

      • So the “please select a mailing list” message won’t go away? Ill have to see what might be happening there.

  • Any chance there’s interest in adding “tags” support to send to Mailchimp?

    • Can you elaborate what you’re looking for? I don’t know what “tags” are in that context.

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