I reached out to Mailchimp support and it appears that the issue is with Akamai (see below), not the Contact Form 7 MailChimp Extension.
My site is hosted on a shared server so I reached out to customer support to see if they could change my site’s IP address. It took them 7 days to respond and in the meantime, the issue managed to resolve itself by simply waiting the Akamai block out. I just tested it (without making any changes) and the extension successfully worked as expected.
*** FROM MAILCHIMP SUPPORT ***
Hello,
Thank You for reaching out to our Mailchimp Tech Support Team, I can definitely understand the concern there and would be happy to help out.
The response you’re seeing is generated from one of our upstream providers, Akamai. Akamai is a service that filters incoming requests by IP address, and denies any requests that do not pass filter criteria. This response indicates that the IP address that your internet connection is using has registered some sort of block with Akamai.
I looked up that reference number and can see that the IP address was recently associated with several malicious actions taken against Akamai managed URLs. Since Akamai sees around 20% of all internet traffic, you might’ve seen this issue when connecting to other applications with the same IP.
Now this doesn’t mean that you did anything wrong at your end whatsoever. This information is reflective of the behavior coming from that particular IP address, which other people may be using as well. Unfortunately, Akamai, or any other web service, would have no way of differentiating between you and someone else who shares the same IP.
That said, we do have a few suggestions. Since the error is specific to the IP address, changing the IP address should help move things forward.
This can be done in multiple ways:
* Wait it out. Blocks of this nature can clear just as quickly as they were implemented, assuming the behavior in question has stopped.
* Clear cache and cookies, disable browser extensions, attempt to browse the app using an incognito window.
* Access the application (make your API requests) from a different network/or from behind a proxy/through a VPN
* If the requests are generated from a web server: Request a new IP from your hosting provider
* If accessing the application (or making API requests) from a home or business network: Reach out to your Internet Service Provider and request a change of external IP
If you have any other questions or concerns, please do not hesitate to reach back out to us; it’s always our pleasure to assist.