SendGrid inbound parse failure with Azure deployed app

2
votes

I have created a simple ASP.NET Web API app that receives parsed emails from SendGrid. Works well on my machine using a secure tunnel with ngrok. The parsed content of emails is posted to the locally hosted app.

However, when I deploy this app to Azure it does not work. I tried to use both HTTP and HTTPS for the callback URL in SendGrid, but emails are not processed. In the Activity page in SendGrid there is no entry for a Parsed email. And I get back a delivery failure email, for the email that should have been handled by SendGrid.

The response was: 550 no mailbox by that name is currently available

I know the app is reachable because I can do successful HTTP requests to other resources, from the browser or other tools.

Is there something that I might have missed? Some additional configuration, either for the app or in SendGrid?

1
azureemailasp.net-web-apisendgrid

1 Answers

2
votes

The short answer is this:

  • If you use CloudFlare for your DNS, it is highly likely that CloudFlare is stopping the inbound parse posts from SendGrid.

  • Review your Firewall Event Log in CloudFlare (under the Firewall Tab) and see if your Web API "Host" is appearing there.

  • If so, what you'll need to do is whitelist the IP Address range that SendGrid uses to send posts for the inbound parse.

  • Their current IP range for the inbound parse as of today is 167.89.117.0/24 (basically of the IP address from 167.89.117.0 to 167.89.117.255).

Hope this helps you or someone else with this same issue/root cause.