Guides

Development mode

Accidentally emailing real customers from a laptop is the classic mistake. MailingKit makes the safe thing the default and gives you three ways to see your emails without sending them.

#Nothing is sent until you say so

If MAILINGKIT_PROVIDER is not set, MailingKit uses the console provider. Every email is printed to the terminal and nothing leaves the machine:

========================================================================
MailingKit console provider: this email was NOT sent
------------------------------------------------------------------------
From:     Example App <no-reply@example.com>
To:       ada@example.com
Subject:  Welcome to Acme Cloud, Ada
------------------------------------------------------------------------
Welcome, Ada

Your Acme Cloud workspace is ready.

Open your workspace (https://app.example.com)
========================================================================

Set MAILINGKIT_CONSOLE_SHOW_HTML=true to print the HTML body too.

#Preview real emails as .eml files

MAILINGKIT_PROVIDER=file
MAILINGKIT_FILE_DIR=.mailingkit/outbox

Each email is written as a standard .eml file. Double-click one and your mail client (Outlook, Apple Mail, Thunderbird) shows exactly what the recipient would see, with attachments and inline images. Add .mailingkit/ to your .gitignore.

#A local inbox with Mailpit

For a browser inbox, run Mailpit and point the SMTP provider at it. This also exercises the real SMTP path:

docker run --rm -p 8025:8025 -p 1025:1025 axllent/mailpit

MAILINGKIT_PROVIDER=smtp
MAILINGKIT_SMTP_HOST=localhost
MAILINGKIT_SMTP_PORT=1025
MAILINGKIT_SMTP_SECURITY=none

Then open http://localhost:8025.

#Staging: redirect everything

Staging should use real delivery, but never reach real users. Set one variable and every email, from every code path, goes to one inbox instead:

MAILINGKIT_REDIRECT_TO=qa-team@example.com

The original to, cc and bcc recipients are removed and listed in an X-MailingKit-Original-To header so testers can still see who the email was meant for. SendResult.redirected is True for these sends.