HttpRequestException - SendGrid Email API v3 integration on a 1&1 Ionos plan

Question

I have had an integration problem when hosting my web application in production, and an unanswered support ticket with SendGrid that was created 5 days prior (at the time of writing this). 1&1 have assured me that all ports are open.

My SendGrid Email API (v3) is working perfectly well in development and when I deploy to a site on my network - I have been using an implementation similar to this: https://app.sendgrid.com/guide/integrate/langs/csharp.

When I deploy to my 1&1 Ionos webspace and test I receive the following error:

System.Net.Http.HttpRequestException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

---> System.Net.Sockets.SocketException (10060): A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken) --- End of inner exception stack trace ---

I am starting to despair as this has caused something of a road block on a project of mine.

[EDIT]

I have just tried a httprequest using a different API and I get the same error. So it must be a server problem with 1&1, but what do I tell them?

Answer 1

I proved the problem was with 1&1, not SendGrid, by testing with another API and getting the same error. Turns out 1&1 hosting uses a proxy server and I need to amend my SendGrid integration to use a web proxy. I discovered this: http://tutorials.moedesign.de/blog/proxy-on-ionos-11-webhosting/

which led me to this help provided by 1&1: https://www.ionos.co.uk/help/hosting/net/script-examples-for-establishing-external-http-connections-windows/

Quite why they couldn't inform me of this when I rang for support is beyond me.