Connection Reset Issue When Accessing Constant Contact API

Hello,

I’m experiencing connection issues when trying to access the Constant Contact API at https://api.cc.email/v3/contacts. Specifically, the connection is being forcibly reset by the server during the TLS handshake.

Here are the details of the problem:

• Using curl or openssl s_client to connect to api.cc.email:443 results in a connection reset (Error 10054).

• TLS handshake fails immediately; no server certificate is returned.

• My environment supports OpenSSL 3.0.11 and TLS 1.2.

• The server IP resolves correctly, but connection is closed/reset immediately.

• This suggests a firewall, WAF, or some network security device on your side may be blocking my requests.

Do I need to verify if my IP or network is being blocked or if there are any special requirements for accessing the API (e.g., IP whitelisting, required headers)?