smtplmail

smtplmail is a drop-in replacement for sendmail, designed to send emails from Linux systems using SMTP. It provides a simple way to configure and use SMTP for outgoing mail, making it easy to integrate with existing systems that expect sendmail functionality.

Features

• Easy setup and configuration
• Support for SSL, TLS, and unencrypted connections
• Configurable via YAML file, environment variables, or command-line flags
• Logging support with configurable log levels
• Sendmail-compatible command-line interface

Installation

1. Download the latest release binary from the Releases page.

2. Run the setup process as root:

   sudo ./smtplmail --setup
   

   This will:

   • Prompt you for SMTP configuration details
   • Create the configuration file at /etc/smtplemail/smtplemail.conf
   • Move the binary to /usr/local/bin/smtplmail
   • Create a symlink at /usr/bin/sendmail pointing to the smtplmail binary

Configuration

The configuration file is located at /etc/smtplemail/smtplemail.conf. Here's an example configuration:

smtp_user: your_username
smtp_password: your_password
smtp_host: smtp.example.com
smtp_port: "587"
smtp_security: TLS
send_from: your_email@example.com
log_file: /var/log/smtplemail/smtplemail.log
log_level: error

You can also set these values using environment variables or command-line flags.

Usage

smtplmail can be used as a drop-in replacement for sendmail. It accepts email content via stdin and supports various command-line flags:

smtplmail [options] recipient1 [recipient2 ...]

Command-line Options

• -f: Sets the envelope sender address
• -F: Sets the sender's full name
• -N: Specifies delivery status notifications (NEVER, SUCCESS, FAILURE, DELAY)
• -v: Enables verbose mode for detailed output
• -i: Ignores single dots on a line
• -t: Reads recipients from the message headers (To, Cc, Bcc)

Configuration Flags

These flags can be used to override the configuration file settings:

• --config: Specify an alternate configuration file location
• --smtp_user: SMTP username
• --smtp_password: SMTP password
• --smtp_host: SMTP server hostname
• --smtp_port: SMTP server port
• --smtp_security: SMTP security (SSL, TLS, or None)
• --send_from: Default "From" email address
• --log_file: Log file location
• --log_level: Log level (error or info)

Examples

Send an email using the configuration file settings:

echo "Subject: Test Email
This is a test email." | smtplmail recipient@example.com

Send an email with a custom sender:

echo "Subject: Test Email
This is a test email." | smtplmail -f sender@example.com recipient@example.com

Send an email using recipients from headers:

echo "To: recipient1@example.com
Cc: recipient2@example.com
Subject: Test Email

This is a test email." | smtplmail -t

Logging

Logs are written to the file specified in the configuration (default: /var/log/smtplemail/smtplemail.log). The log level can be set to "error" or "info" in the configuration file or using the --log_level flag.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. I am still learning Go so I welcome help and advice on best practices. One of the things I was going to do is split the config and mail sending into separate files for better management.

License

Released under the MIT license