Cross-posting and Duplicates

If cross-posting is allowed, this setting determines what people who are members, of more than one list, will receive. Note that Archives must be be kept for at least one day for cross-posted duplicates to be removed.

For example, if a message is posted to two lists and one person (one email address) is a member of both those lists, the person will receive two copies of the posting, one from each list. This is the default behavior, indicated by the setting "cross-posted copies should be sent to recipients as listed"

However, in many situations, you would want each member to receive only one copy of the cross-posting. This is possible, with the setting "make sure that multiple copies of cross-postings are removed".

An example will help clarify how this feature works. Say, you have several announcement lists where you post articles about various topics. You have lists named "computers", "cooking", "gardening" and "sports". People join the various lists that they are interested in. Some people join just one list, while others might join several lists.

Now, say that you have an announcement about a "video game for playing soccer" and you feel that it is appropriate for both the "computers" list and the "sports" list.

If you post your message to both "sports" and "computers" (i.e., you are "cross-posting" your announcement) people who are members of these two groups will receive your announcement.

If you are set to "cross-posted copies should be sent to recipients as listed" then someone who is a member of both "sports" and "computers" will receive two copies of your message, one from each mailing list.

If you are set to "make sure that multiple copies of cross-postings are removed" then someone who is a member of both "sports" and "computers" will only receive one copy of your message. They will receive the message from the first group you sent the message to. Thus, if you posted your message To: "soccer, computers" then the "soccer" messages are distributed first and that is where the person will get their message from.

This feature is particularly useful with announcement lists where you want to split your lists into various topics but often you have messages that apply to several topics. With other list managers, people would receive multiple copies. With ListManager, the duplicate messages are removed and people only receive one copy.

Note: This feature only applies if you have set your list to allow cross-posting. See "Allow Cross-posting".