Lyris User's Guide
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Duplicate messages
Table of Contents
Lyris 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 extensions
Confirmed subscriptions
Duplicate messages
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 Posting Security
Security Considerations of the From: field
Security Recommendations for Announcement lists
How Lyris Determines the Identity of the Person Posting
Lyris Mail Merge
The Lyris command line
Modifying lyris.plc
Add-On Packages
Installing and Upgrading
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 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 is set to reject duplicate postings within a 2 day time period.

Lyris 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 character 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 servers do), instead of the first 200 characters, then a mail loop could occur.

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

Other pages which link to this page:
  • Security Features for Posting Messages
  • Page 382 of 556