Lyris User's Guide
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Duplicate messages
Table of Contents
· Introduction
· Email Commands
· Web Interface for Users
· Server Administrator
· Site Administrator
· List Administrator
· Other Topics
· · Security Considerations
· · Security Issues Relating to Members
· · · Access to the list archives
· · · Access to the list of members
· · · Access to Subscribe to the Mailing List
· · · Steps to restrict false impersonations
· · · Security Features for Posting Messages
· · · · List admin posting
· · · · Admin Moderation
· · · · Number moderating
· · · · Allow Non-Member Posting
· · · · Action Phrase Restrictions
· · · · Password based posting
· · · · Banning members
· · · · Disallow Email Posting
· · · · Secure HTTP web interface
· · · · Lyris List Manager extensions
· · · · Confirmed subscriptions
· · · · Duplicate messages
· · · · Cross-posting
· · · · Maximum posts per member
· · · · Maximum quoting allowed
· · · · Maximum Messages Per Day
· · · · Limit the Message Size
· · · · Reject Email Attachments
· · · · Moderator auto-approval
· · · · Command detection
· · · · Anonymous Postings
· · · Access to unsubscribe and change settings
· · · Visibility of the existence of the mailing list
· · · Web Interface Access
· · · Overview of Lyris List Manager Posting Security
· · · Security Considerations of the From: field
· · · Security Recommendations for Announcement lists
· · · How Lyris List Manager Determines the Identity of the Person Posting
· · Lyris List Manager Mail Merge
· · The Lyris List Manager command line
· · Modifying lyris.plc
· Add-On Packages
· Installing and Upgrading
· Appendix
· Frequently Asked Questions

Duplicate messages

On a discussion list, people will sometimes send the same message several times to a mailing list.

Also, people will sometimes put an automated program on their email address, which answers each message it receives with a standard document. If that document should make it through to the mailing list, the second time that document is posted, Lyris List Manager will detect it as a duplicate posting because it is identical to the previously sent message.

This is known as a "duplicate message posting", and by default, Lyris List Manager is set to reject duplicate postings within a 2 day time period.

Lyris List Manager checks the first 200 characters of a message (about 3 lines) to see if it is a duplicate. The reason for checking only the first 200 characters is because some automatic response programs quote the previous message when they respond. Thus, causing each automatic response message to look "unique". If the entire message were used (as some list managers do), instead of the first 200 characters, then a mail loop could occur.

Note: Duplicate messages are counted on a per-member basis: if two different people send the same message, it is not seen as a duplicate.

Other pages which link to this page:
  • Security Features for Posting Messages
  • Page 424 of 629