Bubble has a deep integration with SendGrid offering the ability to add Sendgrid API keys directly in the Bubble settings tab (once you've added your own domain name). However, the integration doesn't make use of SendGrid's more recent templates and features.
In this Bubble.io video we explain the importance of picking a reliable transactional email provider. Nearly all the emails you send from your Bubble app will be transactional emails and there are a series of things to consider that will improve deliverability and decrease the likelihood of your emails going into Spam or Junk. This video gives an overview of my thoughts about SendGrid, Mailgun and Postmark.
In this Bubble.io tutorial video we demonstrate how to link Postmark and Bubble with the API connector.
In this Bubble.io tutorial video we demonstrate how to create a simple contact form within your application. When the form is submitted we'll trigger a Workflow that sends an email to you with the contents of the form.