Mass mailings

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The term mass mailing may be used to refer to cases of sending a certain message to all users hosted at a site, or to all users in some domain, or to all users in some organization unit, or to all members (including "external" members) of some "large" mailing list, etc.---any case where the number of recipients is relatively "large". The purpose of the message might be one of great urgency (such as an emergency communication), or it might be of general interest but low urgency (such as routine announcements).

Since the MTA supports LDAP filter based (so-called "dynamic") group and list definitions, it is straightforward to define a list or group to consist of all users meeting some criteria (any criteria that may be specified in an LDAP URL filter). See in particular the MTA's support of memberURL and mgrpDeliverTo attributes (or more precisely, those attributes named by the ldap_group_url1 and ldap_group_url2 MTA options) in LDAP group entries. Or for MTA alias file defined groups and lists, see the LDAP URL membership syntax discussed in Alias file LDAP URL alias values. And more complex lists can be constructed, including criteria-based sets of locally-hosted members along with external members listed by address, or lists with "nested" definitions of sub-lists, or "overlapping" definitions/membership.

Groups and mailing lists are most often defined to make use of actual e-mail addresses: either directly as a list of e-mail addresses, or by defining the membership to be users who each have a canonical e-mail address. However, the MTA, via its new in MS 6.3 ldap_url_result_mapping MTA option (and whatever LDAP attribute ldap_url_result_mapping names), also supports defining groups and mailing lists for which e-mail addresses are constructed from other LDAP attributes that do not themselves contain proper e-mail addresses.

Furthermore, as of MS 6.3 and its new process_substitutions MTA option, it is possible to define "meta-groups" and "meta-lists": where a single meta-list definition provides what amounts to an entire collection of definitions of different lists.

As of 7.0.5 and its new GROUP_AUTH mapping table, it is possible to use alternate LDAP attributes and values for group/list authorization checks. In particular, this can be useful when dealing with group/list information stored in an LDAP directory using a non-Oracle schema.

Now any time that a group or list with "large" membership of e-mail recipients is defined, and any time that a message is to be sent to an especially "large" number of recipients, there are some issues worth considering; these issues will each be discussed in greater detail in sections below.

  • Defining the actual list membership; see Defining_membership_of_large_lists.
  • Sensible error handling; see Proper use of lists rather than groups.
  • Restrictions on senders; see Restricting posting access to large lists.
  • Performance in submitting the message; see Performance submitting mass mail messages.
  • Impact of this message (and possibly its multiple copies requiring processing) on other message processing; see Addresses per message copy.
  • The appropriate choice of processing priority for the message. This may vary from "urgent" for messages that are time-critical, to "non-urgent" for messages that while of general interest are not time-critical and might be more efficiently processed during "off hours". (Note that "importance" is a separate measurement than "processing priority": messages can be time-critical but not very important, as for instance a message that a party is about to start in the coffee room, or important without being time-critical, as for instance a message that system down-time is scheduled for two weeks away.)
  • The timing of attempting delivery of the message: for some messages, it may be desirable to delay even attempting to deliver the message until some pre-determined time. See SMTP SUBMIT FUTURERELEASE support.
  • Efficient storage of the messages; see Addresses per message copy.

See also: