The most important consideration is whether your message is on-topic for the list or not. Before posting for the first time, read the mailing list archives (if available) and spend some time monitoring the list without posting so you get a feel for the kind of discussion being conducted through the list.

This is called "lurking" and—although this word usually has bad connotations in English—in this context it is a noble, unselfish act for which your fellow subscribers should thank you. Unfortunately, they are likely to notice only if you post off-topic messages, which will usually be taken as evidence that you haven't spent any time lurking. In these cases some other subscriber may post a flame in response. If you've read this document and followed this advice, you may respond by privately emailing the flamer to confirm that you are indeed aware of netiquette and have been lurking on this list. So there!

A good rule of thumb on whether you should post a message is to consider whether your post will be of interest to more than one or two other mailing list users. If not, then don't post it to this list.

Advertisements and solicitations of any kind are considered spam, and are always off-topic in discussion groups. If you are seeking employment, use the job board.

Most overly long posts are the result of including the entire contents of the message to which you are responding. When you need to quote certain parts of the original post, include only what is necessary to put your comments in context. Brevity is not just the soul of wit (Shakespeare), in an era when the sheer volume of email tends to overwhelm the Enterprise like tribbles (Roddenberry), long email is generally considered bad form.

Long messages seldom serve their intended purpose anyway. If the subject is complex or emotionally charged, it's better to take the conversation offline and handle it via phone or in person. Email is notorious for it's inability to convey emotional tone and the longer and more complex the email is, the more possibility someone may take exception to some part of the contents.

If you want to distribute a large file or a file of an unusual type, such as an video clip, its better to upload the file to a document repository or server and include a link to the file in your email, rather than sending the file to everyone. Large files can slow the delivery process and if sent to a large number of recipients, can affect overall system performance. Large attachments can be problematic for recipients as well, potentially running afoul of mailbox storage limitations. Files of unusual types are may be screened out by firewalls and virus protection software.

Netiquette varies from list to list, but even if something isn't explicitly against list policy, use your best judgment. Remember, you are representing your company or organization and your posts will help shape your professional reputation.

Always assume your email is public. Your email will travel through random servers where anyone with server access can read it, including prying sysadmins and system intruders. An email you intend to keep private may be received by someone who forwards it to an entire mailing list. Think twice before saying anything you might regret later. Once sent, an email takes on a life of its own, it may be forwarded to any number of people, posted to mailing lists and added to archives that may still be publicly accessible twenty years from now.