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Asynchronous transaction-aware MailHost replacement for Zope 2

Project description

The MaildropHost product provides support for sending email from within the Zope environment using MaildropHost objects. Unlike the built-in MailHost object, the sending is done asynchronously from a separate process. Furthermore, MaildropHost can optionally integrate with the Zope transaction machinery to ensure that retried transactions do not lead to multiple emails being created.

The advantage is that sending mail from within web pages becomes much faster because invoking the mail machinery can be slow. With MaildropHost the web page will return immediately.

MaildropHost uses a separate Python process to monitor the mail spool inside the product and handle mail in intervals that can be set by the administrator. There are separate start scripts included with the product which can be used to start this monitor process.

Mails that cannot be sent successfully stay in the internal spool. Every attempt to send email is logged to a log file kept by the monitor process. This log file is closed after each maildrop run, so it is safe to rotate it without sending any special signals to the maildrop daemon.

The maildrop daemon that delivers mail supports StartTLS and even authenticated SMTP.

Starting with Zope version 2.11.0-beta the standard MailHost implementation does asynchronous mail handling as well. If you run Zope 2.11 and up you should look at the standard MailHost product first and see if it fits your requirement before installing the MaildropHost product.

Bug tracker

Please post questions, bug reports or feature requests to the bug tracker at

SVN version

You can retrieve the latest code from Subversion using setuptools or zc.buildout via this URL:


Follow these steps to use the product after installation:

  • edit the “config” configuration script in the toplevel MaildropHost folder to reflect your particular needs, or (optionally) add your own config file in a different location on the filesystem. See below for how to use a configuration file from a non-standard location.

  • start the mail spool checker by running the “start_maildrop” script or with the other start scripts included in the package, which can be found in maildrop/bin underneath the toplevel MaildropHost folder. Edit the startup script to point to your chosen configuration file.

  • instantiate a MaildropHost instance in your ZODB; if you created a config file in a different location, specify the filesystem path using the ‘Configuration file path’ setting on the ZMI ‘Edit’ tab.

  • Now you can create emails using e.g. the dtml-sendmail tag and point the sendmail tag to the MaildropHost instance using the mailhost=”XYZ” argument inside the sendmail tag, or by using the MailHost API (see the Zope Help System).

Instead of using dtml-sendmail and a MaildropHost instance you can create email messages any way you like. As long as the formatting is correct (so that the mail spool checker can parse it, see the file SAMPLE_MAIL.txt for an example) and you write it to the spool directory which is at $MAILDROP_HOME/spool (or $MAILDROP_SPOOL if defined) then the mail spool checker will pick it up and try to deliver it.

To add more choices to the ‘Configuration file path’ option in the ZMI, you need to add them to your Zope instance configuration file, zope.conf. You need to create a section named ‘product-config maildrophost’ and list paths as keys starting with ‘config-path’:

<product-config maildrophost>
  config-path-1 /tmp/myconfig
  config-path-2 /usr/local/mail/maildropconfig

The keys must be unique since ZConfig does not allow duplicate keys in a ‘product-config’ configuration section. You have to restart Zope for those changes to be visible in the ZMI.

If you use different MaildropHost configurations you will need to copy the start/stop scripts found in maildrop/bin and adjust the configuration file path accordingly.

Mail file format

The format for a mail file (see SAMPLE_MAIL.txt) is very simple. The first line contains the recipient address, prefixed by “##To:”. The second line is the sender address, prefixed by “##From:”. These are equivalent to the “envelope” sender and receiver addresses.

The next few lines are headers that become part of the message body, they are “To: <recipient>”, “From: <sender>” and “Subject: <subject>”.

The actual message is separated from the headers by a blank line.

Installation requirements

  • a working SMTP server

  • Zope 2.8.0 or higher

  • A UNIX operating system to run the maildrop daemon. It does not work on Windows.


If you do not install MaildropHost as an egg, you can manually copy the MaildropHost folder from Products.MaildropHost/Products/MaildropHost into a place where Zope can find it, like the “Products” directory:

$ cp -r Products.MaildropHost/Products/MaildropHost <zope>/lib/python/Products/

Do not forget to restart Zope afterwards.

You will find a file named “config” in the MaildropHost folder. This file contains all site-specific settings and you must edit it to suit your needs. IMPORTANT: Since this file is also sourced by a few shell scripts you must not put any whitespace around equal (=) signs!

Startup scripts for the standalone maildrop daemon, which processes mail items generated by the MaildropHost Zope product, can be found inside the <MaildropHost>/maildrop/bin-folder. What these scripts do and how to use them is described in a separate README inside that folder.

Upgrade notes

  • 1.21 to 1.22: The configuration file parsing mechanism changed, it’s no longer a Python import. The code will now look for a file named config instead of However, the file contents have not changed, your existing MaildropHost configuration file contents remain valid.

MaildropHost change log

2.3 (2009-10-09)

2.2 (2009-05-29)

2.1 (2008-11-03)

  • compatibility work for Zope 2.11

2.0 (2008-11-01)

  • Switch to releasing MaildropHost as egg

  • clean up Python module preambles based on the standard set by Zope itself.

  • clean up Subversion keyword tagging to use the Id tag all over

  • major test refactoring and simplifications

  • The MaildropHost class is now marked to implement IMailHost, just like the standard Zope 2 MailHost.

  • The configuration file for each MaildropHost instance can now be selected in the ZMI on the ‘Edit’ tab. By default, the dropdown will show the file ‘config’ in the MaildropHost directory. The site administrator can add more paths using the Zope instance configuration file zope.conf. Please see README.txt to find out how.

  • cleaned up the help system content and use the name “MaildropHost” as opposed to “Maildrop Host” wherever possible.

Previous releases



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