This Python script pulls the last 90 days of messages and saves it to a CSV file.

Save_Messages_Past_90_Days.py

import requests
import csv
import datetime

# create CSV file from array or arrays. array structure = [["Sender Type", "Sender Name", "Sent Time", "Message Text", "Read"]]
def write_CSV(row_array, filename):
  with open(filename + '.csv', 'w') as csvfile:
    filewriter = csv.writer(csvfile, delimiter=',', quotechar='|', quoting=csv.QUOTE_MINIMAL)
    filewriter.writerow(["Sender Type", "Sender Name", "Sent Time", "Message Text", "Read"])
    for row in row_array:
      filewriter.writerow(row)

# You can pull messages from any timeframe by specifying the endMs and durationMs
# For example, for messages from between 01/01/2019 and 04/01/2019, the query URL would be 
# https://api.samsara.com/v1/fleet/messages?endMs=1554102000000&durationMs=7776000000
url = "https://api.samsara.com/v1/fleet/messages?durationMs=7776000000"
APIKEY = 'add key here'

# Need valid API key
payload={}
headers = {
  'Authorization': 'Bearer ' + APIKEY
}

response = requests.request("GET", url, headers=headers, data=payload)

data = response.json()['data']
output = []
for messages in data:
  output.append((messages['sender']['type'], messages['sender']['name'], datetime.datetime.fromtimestamp(int(messages['sentAtMs']) / 1000).strftime('%Y-%m-%d %H:%M:%S.%f'), messages['text'], messages['isRead']))
write_CSV(output, "messages - " + datetime.datetime.now().strftime('%Y-%m-%d'))

# JSON individual message structure
# {
# "driverId": 128319,
# "text": "This is a message from dispatch",
# "sentAtMs": 1626710454992,
# "sender": {
#     "type": "dispatch",
#     "name": "Eddy Araujo"
# },
# "isRead": true
# }