IT and communication - Internet:

Why and how to crosspost

When you post a question or article to Usenet, you should normally post to it one newsgroup only. If you post it to several groups, always use crossposting. This document explains in some detail why and how to do that. For a shorter explanation, see How can I post a message to more than one Usenet newsgroup? in the Indiana University Knowledge Base.


Select a group

Generally, post your question or article to the group that is most suitable for the topic. See How to find the right place to post (FAQ). Specifically select a group which is as specific as possible. For example, if your question deals with engineering, don't post it to sci.engr before checking whether your topic actually belongs to one of the more specialized sci.engr.* groups.

If you can't find a suitable group, don't post to an arbitrary sample of groups; that would be very unproductive, and your message might even be considered as spam, against which serious measures can be taken. Instead, spend some time in studying the descriptions of newsgroups (see e.g. the helpful Tile.Net/news resources) and checking, perhaps using Google Groups, what people actually discuss about in the groups.

It is always a very good idea to check the FAQs first, i.e. the lists of answers to frequently asked questions. See the Usenet FAQ archive (or FAQs by Newsgroup at the University of Oxford or List of Usenet FAQ's at OSU). You might not find your question answered there (after all, there's only about 95% probability for that) but the FAQ for a group gives a very good picture of what's commonly discussed in a group.

Why not post to all relevant groups?

Note: These considerations apply to posting a message to several groups in general, whether you use crossposting or not.

You can probably find dozens of Usenet groups for which your message would be on-topic, especially if you count national and local groups too. Why not post to all of them, to get a wider audience? Wouldn't that increase the odds of finding someone who can answer your question, or buy your used car, or join your club, or share your beliefs, or whatever is your intent of posting this time?

The document How to find the right place to post (FAQ) duly warns:

It is considered highly inappropriate to broadcast your message to a wide selection of newsgroups merely to have more people read it. Note also that many people automatically ignore articles posted to more than two or three groups.

In practical terms, there would be a high risk of getting classified as a spammer and boycotted for that very reason. Even if your message won't be cancelled ("unspammed"), the odds are that the more knowledgeable the reader, the more he regards sending a message to many groups as an indication of cluelesnsess. This means that you would get responses mostly from less knowledgeable readers such as

"try this" people
whose eagerness to help greatly exceeds their capability of helping you (and who didn't bother trying it themselves)
"me too" people
who post (or mail) a response which quotes your article in its entirety (always a warning signal on Usenet!), with just a content-free one-liner appended to it.

Why not send again to a different group?

Quite often people repeat their question simply by sending an article another time, to the same group or to another group, if they haven't got any answers (or any answers they like). That's very unproductive.

If you have got unsatisfactory answers, read them again. It is quite possible that you have got the right answer but refuse to accept it (e.g. you asked how to do something and got the answer that it cannot be done) or fail to understand it. If rereading (and consulting any references cited) does not help, consider sending a followup article, asking for clarification. This lets people discuss the topic in the same thread.

If you got no answers, there are several possibilities:

So you should do some study. When trying to solve the problem yourself you might find something useful, e.g. in the sense that you can formulate the question better. Especially in technical matters, it is important to use correct terms.

If you end up with sending your question anew,

Why crosspost

OK, let's assume that you still want to send your message to several groups. (Sometimes there could be a reason.)

You might compose a message, using your favorite program, and post it to one group. Then you could, depending on the program you use, just edit the line that contains the group name and repost, or use some other method of sending messages with identical content as separate postings. This means multiposting: several copies of the text are sent, as separate messages, within different message identifiers and with no connection to each other as far as the Usenet techniques and protocols are considered. This is the completely wrong way. (Well, perhaps there is no perfection in madness. You could also se different headings to confuse things more, or you could type the message copies by hand so that they use different formulations.) To begin with, it's more awkward to you than crossposting. More seriously, it will disrupt the discussion on Usenet, such as answers to your questions and comments on those answers.

Let's assume that you post a question to two groups, say alt.html and comp.infosystems.www.authoring.html (c.i.w.a.h.), as separate postings. Let's optimistically assume that the question is really on-topic for both groups (in our example, that the question is about HTML authoring for the WWW).

First, to see all answers, you need to check what will be posted to both groups. More work for you.

Crossposting is easier than sending separate postings. You don't really need any other reason. The following discusssion is here to tell you why failure to crosspost really disturbs people.

Most readers of the two groups probably read only one of them. (This is particularly true for very active groups like those I have chosen as examples.) If I read c.i.w.a.h. only, I will see your question but not those answers that have been sent to your identical message in alt.html. This is especially harmful if the answers sent to the group I read are all wrong but some answers in the other group aren't. And people will spend their time in trying to find answers to your question, after seeing that it still remains unanswered, without knowing that someone took great effort and solved your problem - in another group.

Everyone who reads both groups will see your article twice, with no obvious indication of seeing something they had already seen. If you used crossposting, most newsreaders would show the article once only to each reader (and even people using other newsreaders would be able to easily see that it's a crossposted article). Don't you think such repetition will make communication more effective!

And people who read both groups will get pissed off when they see, after taking the trouble of answering your question in one group, that an identical question had been sent to another group. There's little one can do then. One could post a followup message to the other group, including a copy of the answer or a reference to it, but in addition to being extra traffic that could have been avoided, it really does not solve the problem. The two replies are distinct articles, and any comments to them will go to the respective groups. Using Followup-To fields referring to both groups could cause more harm than do any good. In any case, there is no way to bring two threads together once the mistake has been made by sending a message to several groups without crossposting.

What is crossposting, and how to do it

Crossposting simply means that a single posting (article) is sent to Usenet so that it is destined to two or more newsgroups. This means that all replies (followups) to it, and replies to it, etc., belong to the same thread. This lets people read them conveniently, seeing how they belong together.

Warning: The rules of a group may forbid crossposting. In such cases, the best action is to decide between sending to that group only and sending to some other group(s) only. Generally, you should not post to a group before reading its rules, which might be found in its FAQ.

The way to crosspost is simply to compose and send one message once, just writing two or more newsgroups names, separated with commas, into the Newsgroups: header. (Use commas only as separators, with no spaces.) How you do that depends on the program you use. Typically, there's a line visible on the screen above the area where to type your message, with Newsgroups: or something similar on it. Just write the names there. Sometimes you might have problems with this - there are so many programs people use for posting to Usenet - but you need to solve them. Inability to find help for problems in the elementary use of one's newsreader is no excuse for causing problems to a very large number of people.

Example. Let's assume you are using Outlook Express for posting to Usenet. In that case, you should before your first posting check the settings: make sure (via the Tools menu and Options submenu) that the news sending format is Plain Text). Assume you have been reading alt.html and wish to post a question to it so that it will go to comp.infosystems.www.authoring.html too, with crossposting. If you click on the "Compose Message" icon when visiting alt.html, the following appears (with some variation between different installations of Outlook Express):
(A window with a menu and a toolbar, followed by Newsgroups:,
Cc:, and Subject: headers, the first of which is prefilled with alt.html.
The message composition area, initially empty appears below them.
Now you could just click on the position after the prefilled text "alt.html", to make the cursor appear there, and type ,comp.infosystems.www.authoring.html. Such a simple approach works on most newsreaders. Using Outlook Express, there is a more convenient way too, which helps in avoiding typing errors you might make:

  1. Click on the small icon before "alt.html" (or whatever appears in its place).
  2. A "newsgroups picker" will appear. It's a separate small window for adding (or removing) newsgroups. It's easy and intuitive to use. Click on "OK" when done.
  3. Now you will see the message composition window, with the Newsgroups: line filled with a list of groups. Just write your message subject and content normally and send it.

Using the more convenient way, OE displays a space after each comma at the "Newsgroup" like. This deviates from recommendable Usenet practice. However, luckily OE sends the message without those spaces.

How to comment on a crossposted article

Generally, when intending to send a comment (reply, followup) to an article, check the list of groups that the article has been sent to. If there's more than one group there, the odds are that the article deserves no answer, and the probability increases as the number of groups increases.

If you send a comment to a crossposted article, your comment will by default get crossposted too, unless the original sended included a Followup-To header. Consider the risks of sending to several groups before acting.

If it's a "spam" article, which contains off-topic material, you wouldn't make things any better by sending a comment article. On the contrary, you would then look rather foolish too. (By the way, "spammers" don't read Usenet articles. They just send data to Usenet.)

If the article has been crossposted to a few groups for a good reason, consider directing followups to your comment to just one of the groups, namely the one for which the issue is most on-topic. You would do this by including a Followup-To header (among the other headers) containing the name of that group.

You may need to use a program-specific method for including such a header. Just as an example, on Outlook Express, when composing your reply, use the View menu, where selecting "Full Headers" will turn on the display of additional headers. You can later turn it off the same way when you don't need them any more.

Your article would then be sent (with crossposting) to all of the groups but replies to it would go to one group only (if the sender does not take a special action to override your Followup-To header). The point is that people who read, say, just one of the groups will see that (part of) the discussion is moved to another group; they can then decide whether to visit that group to see just that discussion.