• Real-time usage check: Fetches the current mail usage from the SMTP2Go API
• Configurable thresholds: Set custom warning and critical percentage thresholds
• Performance data output: Returns Icinga-compatible performance data for both absolute mail usage and percentage utilization

• Python 3
• requests Python library (install with pip install requests)

1. Make sure Python 3 is installed on your monitoring server
2. Install the requests library if not already present:

   pip3 install requests 
   

3. Download or clone this repository and place the script in the plugins folder

   git clone https://github.com/StratoGh0st99/check_smtp2go_usage.git
   cd check_smtp2go_usage
   cp check_smtp2go_usage.py /usr/lib/nagios/plugins/
   

4. Make the script executable.

   chmod +x /usr/lib/nagios/plugins/check_smtp2go_quota.py
   

./check_smtp2go_quota.py --api-key YOUR_API_KEY --warn 80 --crit 90

-a / --api-key (required): Your SMTP2Go API key

-w / --warn (required): Warning threshold in percent (e.g. 80 for 80%)

-c / --crit (required): Critical threshold in percent (e.g. 90 for 90%)

OK - 200 of 1000 mails used (20.00%) | mails_used=200;800;900;0;1000 usage_percent=20.00%;80;90;0;100

1. Define the CheckCommand in Icinga2

   object CheckCommand "check_smtp2go_quota" {
     import "plugin-check-command"
     command = [ "/usr/lib/nagios/plugins/check_smtp2go_quota.py" ]
     arguments = {
       "--api-key" = "$smtp2go_api_key$"
       "--warn" = "$smtp2go_warn$"
       "--crit" = "$smtp2go_crit$"
       }
   }
   

2. Apply the service to a host

   apply Service "smtp2go-quota" {
     import "generic-service"
     check_command = "check_smtp2go_quota"
     vars.smtp2go_api_key = "YOUR_API_KEY"
     vars.smtp2go_warn = "80"
     vars.smtp2go_crit = "90"
     assign where host.name == "myhost"
     }
   

3. Reload Icinga2

   systemctl reload icinga2