If you have emails to send that you need to make those emails HIPAA compliant I would recommend using the services of mailhippo who make it very easy to secure your emails and make them HIPAA compliant.
You need to ensure the emails are being sent securely to your clients and ensure your email service is configured correctly.
If you're unsure on how to get your email service and email server configured correctly you should hire someone who knows out to ensure your email server and service is secure and configured properly.
Also enter into a HIPAA compliant business associate agreement with your email provider and train your staff and anyone else working for you sending emails on how to send emails that are HIPAA compliant.