We support API overrides for all sorts of use cases such as file attachments and hard-coded templates, but now there are four more things you can do on every send call:
Email channel-level overrides - The email channel-level override allows you to set the subject, reply to, from, cc, and bcc email addresses, as well as the HTML and text via an override that will apply to all your email channels within a template (*currently only available for Mailgun and AWS SES)
Email brand overrides - Brand overrides let you replace certain brand design elements via API at the time of send (logo, top bar color, brand colors). See our docs for details.
Slack Unfurl Support - If you’re sending links in your Slack notifications, you now have the option to unfurl them for recipients! More details in our docs
Email Tracking - You can now let Courier know if we should enable open tracking on an Email right from the API call on a per notification basis! Check out our docs for details