postfix_ratelimit 0.1.0

A Postfix milter for rate limiting.
postfix_ratelimit-0.1.0 is not a library.

Postfix_Ratelimit

A Milter for Postfix that limits the number of emails sent from a user within a specified time frame.

Features

  • Limits the number of emails sent per user
  • Configurable time frame and email limit
  • Supports serving multiple Postfix/Sendmail servers

Installation

  1. Install the binary

    cargo install postfix_ratelimit
cp ~/.cargo/bin/postfix_ratelimit /usr/local/bin/postfix_ratelimit

  2. Create a configuration file at /etc/postfix_ratelimit.conf or /usr/local/etc/postfix_ratelimit.conf with the following content:

    # Please change the paths and values as needed
db_file = "/path/to/your/postfix_ratelimit.db"
log_file = "/path/to/your/postfix_ratelimit.log" # Optional but recommended
interval = 60          # Time window in minutes
limit = 20             # Max emails allowed in the time window

Please see the Configuration section for all available options.

  1. Configure Postfix to use the Milter by adding the following lines to your postfix configuration file: 
    # Replace "inet:localhost:12345" with the actual address and port where postfix_ratelimit is listening.
smtpd_milters = inet:localhost:12345
milter_protocol = 6
# To apply it to non-SMTP mail, add:
# non_smtpd_milters = inet:localhost:12345

Usage

You can now run the Milter with the following command:

postfix_ratelimit

You can also create a service to run it in the background.

Signals

You can send different signals to the program to control it:

  • SIGUSR1 (10) prints the currently loaded configuation values to the console
  • SIGUSR2 (12) resets all rate limits by clearing the database
  • SIGHUP (1) restarts the program to reload the configuration file or save the database
  • Termination Signals (2, 3, 15) save the database and stop the program

Configuration

You can configure options like this:

option = value

Options

Option Type Default Description
db_file String (none, required) Path to the SQLite database file used for storing rate limit data. This option must be set manually.
log_file String (none, required) File path to write logs. This option must be set manually. Leave empty for no logging to file.
socket String "inet:127.0.0.1:11847" Address on which the milter will listen, specified as either "inet:IP:PORT" for TCP or "unix:/path/to/socket" for Unix socket.
interval u64 60 Time window for rate limiting, specified in minutes.
limit u64 20 Maximum number of emails allowed to be sent within each interval.
count_recipients bool true If true, each recipient counts separately towards the rate limit.
max_recipients u64 20 Maximum number of recipients allowed per individual email message. 0 for no limit.
per_host bool false If true, rate limiting is tracked separately per sender and per connecting host.
clean_interval u64 120 Frequency, in minutes, at which expired entries are removed from the database.
debug bool false Enables Debug mode which prints extra messages to the terminal.
reject_error bool false Rejects emails that encountered issues during processing.

CLI Options

--config="": Specify an configuration file path. --debug: Enable debug mode. --help: Show help message.