Hey i created myself a customer in RepairBuddy WordPress Plugin.
When i created myself a customer through the Add Customer option. I received confirmation of logins as customer.

After that i created a job for myself as customer. And when i published the job i received first message from your website about my new order.

After that i changed the status of my job and updated the job, i again received email about status update in job.
Then i clicked the Email customer button and i also go the email.
The backend shows the printable screen but on top of that screen there is message email have been sent please look above invoice.

Everything is working fine, i just installed WP SMTP plugin for testing purposes please remove that plugin and everything is working good.