Gmane works as a bi-directional gateway for many of the lists it carries. To post to a list, you can use the news interface or the web interface.
Since Gmane makes it easy to get in touch with a huge number of mailing lists, it could potentially become a spamming gateway. To inhibit that, Gmane requires that users who post through Gmane authorize themselves.
Here's how it works.
People who do not have valid email addresses in their From or Reply-To headers can't use Gmane to post to mailing lists.
Please do not post test messages to any real groups. The test messages will, in all likelihood, be propagated to the mailing list, and you'll look like a right berk. If you want to test, use the gmane.test group, which works just the same way as all the real mailing lists.
Also see the FAQ for more information about problems when posting.
Read-only groupsSome groups are read-only. These are typically groups for announcements, publication or CVS log messages. Other groups are non-public. These are mailing lists that don't accept messages from non-subscribers. If you try to post to either of these kinds of groups, you'll get a bounce message from Gmane informing you of this.
Some non-public mailing lists allow you to subscribe, and then alter the status of the subscription so that it doesn't actually send you any mail. You can then read the group via Gmane, and post to the list "manually" -- by sending mail directly to the mailing list.
If, however, the group is neither read-only nor non-public, Gmane will forward the message to the mailing list (after going through the authorization process described above). The message still might not be accepted by the mailing list. This is usually because the list really is non-public, but isn't marked as such in Gmane. If this happens to you, please send a short mail stating which group is affected to the Gmane administrators, and we'll fix the configuration.
Rejected email addressesIf you post an article to a Gmane group using a Reply-To or From address that points to a mailing list, Gmane will quietly drop the message. So don't do that.
What address is used?The news-to-mail authorization script uses the From header to determine who's sent the message. If the Reply-To header exists, that header is used instead. If you wish From to take precedence over Reply-To, insert a non-empty Gmane-From header as well.
If you wish to redirect replies to your messages back to the mailing list, add a Mail-Copies-To: never header to your messages. That will result in a Mail-Followup-To header being generated by Gmane. These headers are heeded by quite a few mail readers.
If you add a Reply-To header to your messages that points to a mailing list, the message will be silently dropped.
Detailed information (not for the faint of heart)If you really, really want detailed information on how Gmane does news-to-mail, then read this page. If words like "MX" and "C/R" means nothing to you, then don't read the page. Please.