Send Message to a Pinpoint Custom Channel

There are a couple of custom channel examples like this but they all hard code the message. For example, the above sample contains this code:

"""Construct your message here.  You have access to the endpoint profile to personalize the message with Attributes.
`message = "Hello {name}!".format(name=endpoint_profile["Attributes"]["FirstName"])`
"""
message = 'Hello World! - Pinpoint Slack Channel'

I was expecting a custom channel to behave like any other channel. The docs state: "Custom channels in Amazon Pinpoint allow you to send messages through any service that has an API, including third-party services."

Hello there. That's indeed a very interesting use case. Have you had the chance to look at this resource https://github.com/aws-samples/amazon-pinpoint-slack-channel please?

I second this functionality. It makes very little sense that custom channels are not "1st class citizens" of pinpoint in the sense that you can't use the email template builder or SMS builder UI.

What if you already have the sending infrastructure in place (SMS Gateways & SMTP MTAs/relays) and just want to use pinpoint for campaigns and user engagement? Custom channels seem like the right tool to do the job until you find out that you can't actually define your own messages.