Launchpad and email

Quicker interactive testing

There is a script which reads a single mail message from a file (or stdin), processes it as if it had been received by Launchpad, and then prints out any mail generated in response. For quasi-interactive testing of email processing this may be your best bet.


Otherwise, you can configure Launchpad with an incoming mailbox and an outgoing mailer, in a way somewhat similar to what is used in production. This lets you catch mail sent other than in response to an incoming message.

Create the file override-includes/+mail-configure.zcml with contents similar to the following:


    <!-- delete the username and password attributes if you don't use
        SMTP auth -->

        from_addr="[email protected]"
        to_addr="[email protected]"

    <mail:testMailer name="test-mailer" />



    Uncomment me if you want to get copies of emails in your normal inbox,
    via the stubMailer above.  However, tests will fail because they
    depend on using a directDelivery mailer.  See below.

        queuePath="/var/tmp/launchpad_mailqueue" />


    Uncomment me if you want to get test emails in a Unix mbox file, via
    the mboxMailer above.




Zope3 provides two defined mailers out of the box (smtp and sendmail) so most people won’t actually need the mail:smtpMailer tag because the defaults will usually just work. However, several additional mailers are available for you to use, depending on what you’re trying to do.

The mail:stubMailer can be used to forward all emails to your normal inbox via some other mailer. Think of it as a proxy mailer that can be used to specify explicit MAIL FROM and RCTP TO envelope addresses. The rewrite attribute of the mail:stubMailer specifies whether the RFC 2822 headers should also be rewritten. You and your spam filters might prefer this set to true.

The mail:mboxMailer stores messages in a Unix mbox file and then forwards the message on to another mailer. You can use this if you want a record on disk of all the messages sent, or if you’d rather not clutter up your inbox with all your Launchpad test email. The overwrite attribute says whether to truncate the mbox file when Launchpad starts up (i.e. opens the file once in ‘w’ mode before appending all new messages to the file).

The mail:testMailer is necessary for the Launchpad tests to work. You must use a mail:directDelivery mailer for the tests, otherwise you’ll get lots of failures. Basically, the testMailer stores the messages in a list in memory.

For both mail:mboxMailer and mail:stubMailer the mailer attribute specifies the next mailer in the chain that the message will get sent to. Thus if mailer is set to smtp, you’ll get the messages in your inbox, but if it’s test-mailer, the unit tests will work.

Finally, these are all hooked up at the top with either a mail:queuedDelivery section or a mail:directDelivery tag. You must use a mail:directDelivery tag if you want the unit tests to work because otherwise, the in-memory list of the mail:testMailer won’t be updated by the time the unit test checks it.

If you just want the unit tests to work normally, don’t include a mail:queuedDelivery or a mail:directDelivery section at all. Launchpad will DTRT internally. However, if you want copies in an mbox file or in your inbox, set the mailer attribute to the appropriate mailer, chaining that to a mail:testMailer for the unit tests or a mail:smtpMailer for development.


Launchpad code should use the methods defined in to send emails (simple_sendmail, sendmail or possibly raw_sendmail)

Functional Tests

The functional test harness is configured to allow easy testing of emails. See lp/services/mail/tests/ for example code.


To send email from Zope3, you use an IMailDelivery Utility, which defines a single send method. There are two standard IMailDelivery implementations:

  1. QueuedDelivery – email is delivered in a separate thread. We use this for production.

  2. DirectDelivery – email is send synchronously during transaction commit. We use this for tests.

Both implementations will send no email if the transaction is aborted. Both implementations use events to notify anything that cares to subscribe if delivery succeeded or failed. Both implementations look up an IMailer utility by name to do the actual delivery, as specified in the mailer attribute of the queuedDelivery and directDelivery ZCML tags.

Zope3 provides two IMailer implementations out of the box:

  1. SMTPMailer – sends email using SMTP

  2. SendmailMailer1 – Uses the `sendmail program to send email.

In addition to these two, there are three more IMailer implementations for use with Launchpad development (production instances will just use SMTPMailer or SendmailMailer):

  1. StubMailer – rewrites the envelope headers and optionally the RFC 2822 To and From headers before handing on to a different IMailer.

  2. TestMailer – stores the email in memory in a Python list object called for easy access by unit tests.

  3. MboxMailer – stores the email in a Unix mbox file before optionally handing the message off to another IMailer.

Developers (and production server, until we are confident messaging is working fine) should use the StubMailer, like in the quickstart example. This causes all emails to be redirected to the specified destination address to you can test to your hearts content without spamming other developers or innocent civilians. Or you can use the MboxMailer.

The functional test suite is already configured to use the TestMailer. However, if you use a StubMailer or MboxMailer and want the test suite to work, you must hook it up to a TestMailer explicitly. See lp/services/mail/tests/ for an example showing how functional tests can check that notifications are being sent correctly.