There are four mailing lists for SANE: sane-devel, sane-standard, sane-announce, and sane-commit. For details on topics and subscription, see below.
sane-devel is the main discussion list for SANE (Scanner Access Now Easy). Despite its name, it's also intended for users. You need to be subscribed to be able to send mail to this list. If you are not subscribed, your mail may be approved by the moderator but that can take some time. When answering to a posting, keep in mind that the response is directed to the author by default. If you want to respond to the list, please use the "reply-to-list" (or similar) function of your mail client. You can subscribe, unsubscribe or modify your settings by using the web interface.
sane-standard is used to discuss the SANE standard. Topics are the development of the new standard version 2 and missing features and bugs in existing SANE standards. All other topics should be directed to sane-devel. If you are not a developer, sane-standard will most probably be the wrong list for you. Especially this list is not for user support nor asking questions about scanners, software etc. You can subscribe, unsubscribe or modify your settings by using the web interface.
sane-announce is a low-traffic list for release and similar announces. It's intended for users who want to know when a new release or beta snapshot of sane-backends or sane-frontends becomes available. The list is moderated. You don't need to subscribe to sane-announce if you read the sane-devel mailing list as all postings going to sane-announce will be posted to sane-devel, too. You can subscribe, unsubscribe or modify your settings by using the web interface.
When a developer changes the source code of SANE in git, an email containing a summary of the changes is sent to sane-commit. If you are interested in changes in the SANE source, this list is for you. The list is read-only, there no archive either. You can subscribe, unsubscribe or modify your settings by using the web interface.
You can also subscribe to the mailing lists by sending a mail containing the word "subscribe" in the subject to firstname.lastname@example.org (exchange devel by the respective list name). To unsubscribe, send a mail containing "unsubscribe password" to that address. You get the password by email once you have subscribed. If you lost your password, use the web interface to get it send to you again.
The SANE IRC channel #sane (irc.freenode.net) is intended for discussions about SANE and for getting help. Please be patient, answers can take some time. Please read the documentation before asking. Tell us which scanner, which operating system and which version of SANE (scanimage --version) you use.