Integrating Postmark with Rails Solidus: Best Practices for Development, Staging, and Production

Integrating Postmark with Rails Solidus for email handling is an essential step for ensuring reliable email delivery. However, it’s important to make sure that emails aren't accidentally sent from non-production environments, which could lead to test emails or worse—real customer data being sent out.

Step 1: Setting up Postmark API Key

Start by creating an account with Postmark and generating API keys for your different environments.

• Production: In Postmark, create a server specifically for production and generate an API key for it.
• Development and Staging: For these environments, you can use Postmark's "test" API key to prevent actual emails from being sent, or alternatively, configure your environment to block outgoing emails entirely.

Step 2: Configuring Rails for Postmark

Ensure that your Rails environment configuration files point to Postmark for email delivery. You can set this in your config/environments/production.rb, config/environments/development.rb, and config/environments/staging.rb files:

# config/environments/production.rb
config.action_mailer.delivery_method = :postmark
config.action_mailer.postmark_settings = { api_key: ENV['POSTMARK_API_KEY'] }

# config/environments/development.rb
config.action_mailer.delivery_method = :postmark
config.action_mailer.postmark_settings = { api_key: ENV['POSTMARK_API_KEY'] }

# config/environments/staging.rb
config.action_mailer.delivery_method = :postmark
config.action_mailer.postmark_settings = { api_key: ENV['POSTMARK_API_KEY'] }

Make sure the POSTMARK_API_KEY environment variable is set correctly for each environment.

Step 3: Avoiding Accidental Emails in Non-Production Environments

To ensure no emails are sent from development or staging, one strategy is to conditionally use letter_opener for non-production environments, allowing you to preview emails locally rather than sending them out. You can configure this as follows:

# config/environments/development.rb
if Rails.env.production?
  config.action_mailer.postmark_settings = { api_key: ENV['POSTMARK_API_KEY'] }
else
  config.action_mailer.delivery_method = :letter_opener # For safe email preview
end

However, if you're unable to use letter_opener (for example, in a CI/CD pipeline or on a server), Postmark provides another powerful feature: sending emails to a "black hole".

Step 4: Using Postmark's Black Hole for Testing

Postmark offers a feature that allows you to send emails to a black hole. This means that instead of sending emails to real recipients, Postmark simply discards them. To use this, you can configure your Rails app to use a dummy email address in development and staging, for example, [email protected].

By doing this, you ensure that emails are routed to a "black hole" where they won't reach anyone but won't affect your real production environment either.

You can configure this in your environment settings like this:

# config/environments/development.rb
config.action_mailer.default_options = { from: '[email protected]' }

# config/environments/staging.rb
config.action_mailer.default_options = { from: '[email protected]' }

This way, any emails sent during development or staging will go into Postmark's black hole instead of being delivered to real addresses.

Pitfalls to Avoid

• Accidental Email Delivery: If Postmark’s black hole or letter_opener is not set up correctly, there's a risk of sending real emails during testing. Always verify that your development and staging environments are properly configured to prevent this.
• Mixing Production and Test API Keys: Be mindful not to mix up your API keys between environments. Using the wrong key could result in emails being sent from the wrong environment.
• Overlooking Environment-Specific Settings: Always ensure that your environment settings for email delivery are correctly configured, especially when deploying to staging or production. If you're unsure, always test with a mock email or using the black hole functionality.

Conclusion

By taking these precautions and setting up Postmark properly for each environment, you can ensure safe email handling across development, staging, and production. Using tools like Postmark’s black hole feature or letter_opener will help you avoid sending test emails by mistake, safeguarding your customer communications.