smog

smog

A cross-platform SMTP to Gmail API relay tool.

DESCRIPTION

smog acts as a local SMTP server that accepts authenticated email submissions and relays them through the Google Gmail API using OAuth2. It is designed for legacy systems that can only send email via SMTP ut need to integrate with a modern Gmail account.

Before first use, the administrator must run smog auth login to authorize the application with Google. The GoogleCredentialsPath configuration option must be set to the path of the credentials.json file downloaded from the Google Cloud Console.

Important Note on Bcc Handling: Due to limitations in the Gmail API when sending raw email data, this tool cannot preserve the privacy of Bcc (Blind Carbon Copy) recipients. All recipients from the RCPT TO SMTP command, including those intended for Bcc, will be visible in the final email's To: header.

USAGE

 smog [global flags] [command]

GLOBAL FLAGS

 -c, --config <path> - Specify a custom path to the smog.toml configuration file.

 -v, --verbose
       Enable verbose logging output to the console.

 -s, --silent
       Disable all console output except for fatal errors.

COMMANDS

 serve
       Starts the SMTP server and begins listening for connections.
       This is the primary operational mode and the default command.

 auth
       Manages Google API authorization.
       login     Initiate the interactive OAuth2 flow to authorize
                 smog to send emails on your behalf.
       revoke    Delete the stored API token. Re-authorization will
                 be required on the next run.

 config
       Manages the configuration file.
       create    Creates a new, default smog.toml file in the
                 platform-appropriate default location.
       show      Displays the currently loaded configuration.

 version
       Prints the version of smog.

 help
       Displays this help message.

FILES

 smog.toml is the default configuration file. It is searched for in the
 current directory, and in the following platform-specific locations:

 Linux
       /etc/smog/smog.toml
       /var/lib/smog/smog.toml

 macOS
       /Library/Application Support/smog/smog.toml

 Windows
       C:\ProgramData\smog\smog.toml

EXAMPLES

 Run the SMTP server with the default configuration:
       $ smog serve

 Authorize smog with your Google account:
       $ smog auth login

 Run the server using a custom configuration file and verbose output:
       $ smog -v -c /etc/custom/smog.toml serve

LICENSE

Copyright (C) 2025 Ethan Piliavin

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.

AUTHOR / CREDITS

Ethan Piliavin - Architect and Vibe Coder :)
Google Gemini - Planning and Documentation
Google Jules - Engineering