Owner Guide

1. Introduction to Ezmlm

The mailing list service has been provided using EZMLM for over 10 years but a project is currently underway that is programmed to complete in mid-2014 to replace this software with a more modern alternative that will provide a more user-friendly management interface and functionality more suited to current use requirements.

This document is intended for list owners on the EZMLM system and shows you how to configure your mailing list. If you are looking for information on how to subscribe or be removed from an ezmlm list please click the following link: Subscribing/Unsubscribing from ezmlm mail lists.

2. Getting started

To edit your mailing list configuration settings, you should log into your account using your Single Sign-On username and password at the following address: https://maillist.ox.ac.uk/

The mailing list welcome screen is shown below:


Your mailing list homepage hows all of the mailing lists you own. Each list can be opened for editing from here. By the side of each list name there are 6 links: Each link below takes you to an example page for that category. Detailed instructions on how to use these settings are found in other sections of this document.

This setting allows you to configure how your mailing list will work (see following sections of this document).
This setting allows you to add users to your mail list.
This setting allows you to add moderators to your mail list.
This setting allows you to include additional email addresses for the same person. They can then send messages to the list from each address. You can also add unsubscribed people to this list and allow them to post to your list.
This setting allows you to prevent messages from being posted from particular email accounts.
This setting allows you to edit the standard messages your subscribers receive from the mail list.

3. Mailing List Configuration

The mailing list configuration manager is found by selecting 'Config' from the mailing list homepage. You will then see the following web page:


Part of the Configuration web page showing the        archive section.
Figure 1. Part of the Configuration web page showing the archive section.

Your mailing list preferences are set using the configuration manager.

Please Note:

Some options need to be selected first and these changes saved BEFORE secondary options appear in boxes at the foot of the page. Further editing will then be necessary to complete the setup. This is caused by the underlying programme running the ezmlm software. In the following sections this effect is highlighted where it occurs.

4. Controlling who may subscribe and unsubscribe

The Subscriptions panel on the configuration page controls who who can subscribe and unsubscribe to your list. There are 2 options:

  1. List will respond to any subscribe and unsubscribe requests and allow public archive retrieval.
  2. Subscription requests to the mailing list and digest will be passed to the moderators.

People are required to confirm that they wish to subscribe to or unsubscribe from a mailing list when they make a request. There is, however, no confirmation process when members are subscribed or unsubscribed by the list administrator via the web interface. List administrators will need to send out a welcome message if they wish the new members to receive one.

When a list has subscription moderation turned on and someone requests subscription to the list they will first be asked to confirm their request then it will be passed on to the subscription moderators for them to accept or reject.

4.1. Allow subscribe and unsubscribe requests

If you want people to be able to request to join or leave your mailing list then you will need to select option 1. If you do not select this option then any requests to join or leave will be rejected.

4.2. Moderation of subscribe requests

If you want to control who can join your mailing list, select options 1 and 2.

Please Note: Option 2 sets moderation of subscriptions only. In most cases you should let people unsubscribe from your list if they really want to.

5. Controlling who may post to a list

You can control who posts to your mailing list in several ways. Some options are dependent on each other so combining options in the web interface may not always give exactly what you expect.

Control over posting rights is defined through five options in the Posting panel on the configuration web page (shown below). Changes here affect the workings of four lists, these are: the Subscribers list, the Moderators list, an Allowed Posters list and a Denied Posters list.


The Postings panel has 5 options. Selecting options here modifies the workings of the 4 standard lists (subscribers, moderators, allowed and denied lists).

  1. Posts from addresses other than those in the Allow Posters list will be rejected. This is most useful when you want to limit those who can post to a small group whilst also passing all (un)subscription requests to a separate list of moderators.
  2. Posts to the mailing list from addresses in the Deny Posters list will be rejected.
  3. All posts to the mailing list will be moderated.
  4. Posts from addresses other than moderators will be rejected.
  5. Allow subscribed email addresses to post to the list. Posts from addresses which are not subscribed to the list will be rejected unless they are added to the Allow Posters list.

Select those options you require and save your changes by pressing the Make changes button at the foot of the page.

5.1. Open access

If you do not select any of the Posting options listed above then the list will be completely open to posts by the general public.

5.2. Blocking certain addresses

If you have a mailing list where anyone can post, or possibly posting is limited to subscribers, you may wish to block certain addresses that are continually causing trouble on the list or posting large quantities of unwanted spam mail. In this case you can turn on option 2 above and put their addresses into the Deny Posters list.

This is not a complete solution as it is very easy to obtain a new email address to post from but it can be useful in some situations.

5.3. Subscribers + allowed posters only

Commonly list owners want to limit posts to subscribers only. To setup this configuration select option 5 from the list above. It can be combined with option 2, to deny posting rights for certain members.

In Oxford people often have more than one email address (e.g. a college address and a departmental address). A good working solution to this problem is to add one form into the subscriber list and the other into the Allow Posters list so that the list member does not need to worry about which address they are posting from, either would be accepted by the server. Only the address in the Subscriber list will receive mail from the list.

5.4. All posts moderated

If you need to check all posts to the list before allowing them to be posted you should turn on option 3 in the Postings panel. This means all messages, no matter who they are from, are sent to the moderators. You must specify at least one email address in the moderators list otherwise postings to the list will not be moderated.

For details on how the moderation system works see Moderating messages and requests.

You can also completely block messages from specified users by using the Deny Posters list. In which case posts from those addresses would be silently dropped and not passed onto the moderators.

5.5. Subscribers + others moderated

You may want to allow subscribers to post without any moderation and also allow non-subscribers to post but with moderation to block unwanted messages, such as spam. In this case you should select options 3 and 5 together.

As above, you can also completely block messages from specified users by using the Deny Posters list. In which case posts from those addresses would be silently dropped and not passed onto the moderators

5.6. Moderators only

If your list is intended to be used for announcements only, e.g. a college official mailing list, then you may want to limit posting rights to only those email addresses in the moderators list. If you are not using subscription moderation as well as posting moderation then the moderators will not receive any moderation requests other than for their own messages.

To activate the message moderation system select option 3 and also select option 4 to set up moderator posting only. In this situation the options 2 and 5 will have no effect. This is similar to the Majordomo restrict lists, which creates a small group of allowed posters.

Moderators will be required to self-moderate their posts. This is a security measure to prevent spoofing of email addresses. In self-moderation only the original sender receives a copy of the post instead of all the moderators. Moderation is very simple and is described in Moderating messages and requests.

If you intend to moderate subscriptions as well as posting and you do not want those on your restricted posters list to receive subscription moderation requests then the best solution is to select option 1 instead. See below for details.

5.7. Allowed posters only

This case is similar to the Majordomo restricted poster list. Only those addresses in the Allow Posters list will be able to post to the mailing list.

To set up this situation select options 1, 3 and 4. The configuration system will automatically force options 3 and 4 to be selected if you select option 1 alone.

In this situation those allowed posters will be required to self-moderate their posts to the mailing list as explained in the section above Moderators only. If you turn on subscription moderation those moderation requests will be directed to email addresses in the moderator list rather than the allowed posters list. People on the allowed posters list will not see any moderation requests other than for their own posts as anyone not in the allowed posters list will be blocked.

6. Moderating messages and requests

Moderation of subscription requests and posts is relatively simple. The moderator receives a message asking them to check the request, which is quoted in the message. They should either reply to the From address - to reject the message (it has the reject word in the address) or to the Reply-To address - to accept the message (it has accept in the address). Most email software will automatically select the Reply-To address so it is very simple to accept a message, which will likely be the most frequent case.

If moderators wish to get help they can send a message to listname -help@maillist.ox.ac.uk and it will return a general help page on how to moderate requests.

There is a default time limit for moderation of messages. This is set to 120 hours. After this time any requests that have not been accepted or rejected, will automatically be considered to have been rejected. The time allowed can be set to any whole number of hours between 24 and 240 through the Options panel.

7. Managing obsolete email addresses

One of the problems with mailing lists is that they can quickly become obsolete as subscribers change their email address and do not remove old addresses from lists they are subscribed to. Ezmlm has a method to monitor bounced emails and can remove addresses from which emails regularly return.

Ezmlm uses the subscriber address and message number (encoded within the sender address) to track which message have bounced for which recipient. Since messages can bounce for a variety of reasons, ezmlm does not remove a subscriber from the list immediately. Instead it waits 12 days after the first bounce, then sends a warning message to the subscriber. The warning message lists the numbers of the messages missed. The user can retrieve these from the archive (if this feature has been enabled). If the warning message again bounces back, ezmlm waits another 12 days, then sends a probe message. If this probe message bounces the email address is removed from the subscriber database. This mechanism guarantees that a subscriber will not be removed due to a temporary error, while assuring that all non-existent or permanently failing addresses are removed.

Please Note: Subscribers receiving warning messages and the probe message do not need to do anything with them. Ezmlm is just checking to see if their address will receive its test messages.

8. Archiving and Digests

Digests are not currently supported. Ezmlm maillist archives are available through the email interface. A guide on how to use the archive feature is given in the Ezmlm formal guide. You can also view a list of publically available maillists.

9. Filtering Spam

Spam can be very annoying to subscribers, moderators, and owners of maillists. Subscribers stand an increased risk of receive copies of spam even if they have taken good care over the configuration and management of their own email account; Moderators can be swamped with moderation messages relating to spam that has arrived at the list address; Owners may receive spam that has been detected as (un)subscription requests, complaints from list users, and complaints from third parties who have ended up involved.

9.1. Basic List Configuration to Block Spam

In the Settings panel there are two Spam filtering options that control how the Oxmail spam scoring system is used to reduce spam on your maillist: Enable and Level. By default these options ignore spam scoring - all mail goes through. This is to ensure that a newly create list will faithfully transmit all posts.

A moderate setting that will significantly reduce spam is to tick the Enable option, and leave the Level at the default value of 5.

9.2. Other Options for Controlling Spam

Various other list configuration options have the potential to combat spam as well, but generally affect list operation too. Areas to consider include:

  • Subscription policy: if you manually control list membership and do not provide a list archive then turning off Subscription option 1 can reduce spam, and "back-scatter" resulting from spammers sending mail to the (un)subscription / archive addresses leading to an automated maillist response being sent to the (often forged but valid) sender address used by the spammer
  • Posting options: options 1, 2, and 5 can be used to prevent the list from accepting spam sent from any email address except those specified in your list configuration
  • Header-based filters: configuring your list to reject mail with the Precedence: bulk or Precedence: junk may help to block some forms of circular or unsolicited commercial email

With all of these later options however, there is a risk that you will be altering the behaviour of your list in an undesirable way, and also that some user set-ups result in email being generated that is blocked by some of these settings.

10. Other Options

In this section more specialised features can be set through the Others panel. This is shown below:


Further options are also available under the settings section following on from the Others panel.

10.1. Subject prefix

Ezmlm can be configured to insert a prefix onto the subject of any new message sent to the mailing list. To use this facility select option 1( Outgoing message subject will have a prefix) in the Others panel. Save your changes by clicking the Make changes button at the foot of the page. The system automatically adds the default [listname] into the Subject Prefix box. Alternatively you can insert your own a short prefix into the Subject Prefix, Save any changes you make.



10.2. Message Size

There is a maximum size of 10MB for all messages passing through the Oxford EZMLM system. This is therefore the maximum value you can set for maillist posts. The default maximum size is 3Mb and minimum size of 2 bytes. To increase or decrease these values select option 3 in the Others panel and type in new maximum or minimum values under the Settings section. Save your changes using the Make Changes button.

10.3. Trailers for messages

You may want to add unsubscription details or other information to the end of each post. In order to achieve this, select option 2 in the Others panel. You must now save your changes by pressing the Make changes button, otherwise the trailer trailer text file will not appear in the text file list. Once the configuration file has been saved, select [Text Files] from the main menu. The text files page will now appear and show Trailer as an link. Click on Trailer to edit the default text. The trailer default text is shown below:

      To unsubscribe, e-mail: [list
      name]-unsubscribe@maillist.ox.ac.uk For additional
      commands, e-mail: [list name]-help@maillist.ox.ac.uk

10.4. MIME removal and rejection

Ezmlm provides the ability to strip or block unwanted MIME-type parts of emails. For instance if a user sends a html and text only versions, you can specify that the html version is stripped from the email. Your list members will only receive the plain text part of the email which all email software can handle. If there was only a html part and nothing else the message would be blocked (i.e. returned to sender) instead.

This can also be used to ensure people do not send binary attachments, such as large image files or viruses to your mailing list.

To activate this option you need to select Message blocking and stripping from the Others panel. At this point save your changes. Scroll down to the MIME types to strip from all outgoing mail box. This box will now contain the list of default MIME-types to be stripped or blocked from the mailing list. You can then edit this list as appropriate.



10.5. Headers to add and remove

Ezmlm allows you to add customized headers to all posts and to remove any occurences of specified headers sent through its system. This feature is always in operation, so to make use of it there is no need to turn on any special options. You could, for instance, add a specific Reply-To header to ensure people always reply directly to the list instead of the sender.


There are a couple of "magic" variables that can be used in the headers to be added. These are:

  • <#l#> - The mailing list name
  • <#h#> - The mailing list server name
  • <#n#> - The current message index number (to aid archive retrieval)

You can add these anywhere in your custom headers and they will be translated by the ezmlm software into the correct entries.

10.6. Using an Alias with the Maillist

In the Settings section of the configuration page, there is an option to allow an alias email address to be used with the maillist:

Allowing an Alias Address
Figure 2. Allowing an Alias Address

To use an alias to send email to a list, the checkbox should be ticked. This will disable the checking of whether the list address appears in the To: or Cc: header of messages sent to the list. Most lists will not need this option so it should be left unticked. Please note if you do select this option, you will increase the amount of spam email sent to your list.

To setup or change where a generic alias is routed, contact registration@it.ox.ac.uk

10.7. Nested Lists

Nesting enables an EZMLM list (the "child") to be subscribed to another EZMLM list (the "parent") so that an email sent to the parent list is sent to subscribers of the child list as well as subscribers of the parent list.

Nesting is not enabled by default, but you can request this by emailing sysdev@it.ox.ac.uk with the full address(es) of the child lists that you wish to nest.

Please note the following when considering nesting:

  • Posting messages directly to child lists will not be affected by nesting.
  • Posting messages to parent lists will result in the message being sent to subscribers of the parent list and subscribers of any child lists.
    • If an address is subscribed to multiple lists then multiple copies of the message will be received.
    • The message that subscribers of any child lists will receive will show the address of the parent list in most visible headers (e.g. To:), but will have the address of the child list in most of the additional headers (e.g. Reply-To: and the List-*: headers)
  • Configuration of the child list will still apply - it is usually advisable to have consistent configuration (especially for settings such as maximum message size, accepted MIME types), and do remember that if the child list only accepts postings from selected email addresses then you may need to adjust the permitted sender addresses accordingly.
  • Bounces and other administrative responses relating to subscriber addresses on the parent list will be handled normally.
  • Bounces and other administrative responses relating to subscriber addresses on any child lists may not be handled as you would normally expect as the bounce will typically come back to the child list. This means that the owner of the parent list will not receive any delivery failure notifications for failing addresses subscribed to child lists. Further, for subscribers to the child list:
    • Replies will default to the parent list address.
    • Administrative responses (e.g. unsubscribe) will be sent to the child list (despite the parent list address being shown in the To: header).
    • Delivery failures will cause the bounce/probe process to be initiated for the receipients' subscription to the child list, despite the message having been sent through the parent list - this could be highly undesirable if the receipient has whitelisted the child list but not the parent list.


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Written by IT Services. Latest revision 23 May 2017