I am trying to send a POST request as JSON.

*email variable is of type “bytes”

def request_to_SEND(email, index):
    url = "....."
    data = {
        "body": email.decode('utf-8'),
        "query_id": index,
        "debug": 1,
        "client_id": "1",
        "campaign_id": 1,
        "meta": {"content_type": "mime"}
    }
    headers = {'Content-type': 'application/json'}

    try:
        response = requests.post(url, data=json.dumps(data), headers=headers)
    except requests.ConnectionError:
        sys.exit()

    return response

I get the error:

 File "C:\Python34\lib\json\encoder.py", line 173, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: b'1' is not JSON serializable

Could you please tell me what is it that I am doing wrong?

This is happening because you’re passing a bytes object in the data dict (b'1', specifically), probably as the value of index. You need to decode it to a str object before json.dumps can work with it:

data = {
    "body": email.decode('utf-8'),
    "query_id": index.decode('utf-8'),  # decode it here
    "debug": 1,
    "client_id": "1",
    "campaign_id": 1,
    "meta": {"content_type": "mime"}
}