Any emails you send via OpenCRM will be sent one by one. Behind the scenes, if you schedule a bulk email to 10 recipients, it will individually process and send ten emails. This means you can use merge variables to personalise each mail. If you have multiple campaign mails scheduled to be sent concurrently, they will all be triggered and sent at the scheduled time, rather than being queued. 

Click here to learn more about bulk emailing and email quotas.