Notice that the returned string is slightly different when redirect from HTTP to HTTPS is used. Instead of just a GIF, I got

HTTP/1.1 200 OK
Server: nginx/1.10.3 (Ubuntu)
Date: Wed, 21 Feb 2018 09:31:38 GMT
Content-Type: image/gif
Transfer-Encoding: chunked
Connection: keep-alive

GIF89a\000\000\000\000\000\000\000\000\000\000!�\000\000\000\000,\000\000\000\000\000\000\000D\000;

Without redirect (using https in the URL) I got:

GIF89a\000\000\000\000\000\000\000\000\000\000!�\000\000\000\000,\000\000\000\000\000\000\000D\000;

Awesome thank you 👍 I checked it should work for all PHP versions.

One possible thing to think about: What do we do when there is a location redirect and it is a POST request? The POST request would not re-submit the data AFAIK and the tracking request would not work. Maybe for now we enable it only when $method === 'GET'?

This is the case in all requests but bulk tracking. For POST requests I wonder if we should later rather implement to check if there is a location header in the response, and if so POST the request to that URL? (can be done in a separate PR/Issue)

@olleharstedt are you still working on this PR? Could we add the follow option maybe only for GET requests?

Hi! Was on vacation. Yes, I can modify the PR to include the option only for GET requests.

New PR here: #46