Just so you know
Mailchimp provides security measures to reduce the risk of unauthorized access, including physical security controls and encryption. Since encryption is built into the service, it may meet certain HIPAA compliance regulations, but using Mailchimp doesn’t guarantee that all HIPAA compliance standards will be met.
According to Mailchimp’s terms and conditions, customers are responsible for ensuring they comply with regulations like HIPAA.
Uploading patient information to a Mailchimp email list likely constitutes a disclosure of protected health information (PHI).