We currently have 7,000 clients emails in our database. Can we send an email out to clients to let them know we are using GDPR compliant software?

You can certainly do so, but we need to remind you that GDPR compliance is more than using a GDPR compliant software. Please make sure you and your staff understand what GDPR compliance means to you and your business and prepare accordingly. For example, make sure all those 7,000 emails have consented to receive such emails and are ‘active’ clients (they have visited the salon in the last 18 months or less).