Send out emails to non-contacts via BPM

Hi, 

Our customer uses Sugar Serve and receives lots of cases from people daily. As they want to ensure that they comply with all European laws regarding personal data storage, they do not want to have to store every person who contacts them as a contact in SugarCRM.

They now want to set up a BPM process to send out an email when a case has been closed in SugarCRM. However, it does not seem possible to do this to people who are not registered as a contact. Does anyone have a workaround for this?

We therefore want to make it possible to send an email via BPM to the person who sent in the email linked to the case.

Regards, 
Frida