Rules for the developers mailing list
Apart from the obvious netiquette requirements, please consider the following before sending an email to the list to save everyone's time.
Is your message really of interest for a majority of the 92 readers (December 2012)? Or can the issue be discussed in a smaller group and only the outcome be announced to the list?
Get to the point quickly. Use the forum, IRC or private messages for chatting. This is a working place. ;)
Write in quoted context. Quoting the whole message you are replying to and writing a single sentence at the top is bad style. It will confuse readers and they will lose interest in a thread. Instead, write directly below the sentence you are referring to and cut out all the rest. Leave the "xxx wrote on yyy:" that your email client adds at the top. See the quotes section of the openSUSE mailing list guidelines for details and have a look at the example at the bottom of this page.
Address your audience
Write things like "hi all" or "hello veit and casey" at the top, so people know straight away if they should read on.
If a thread goes a certain direction that has nothing to do with the original email subject, consider altering the subject (e.g. "Name for project (was: Next milestone)") or starting a new thread.
If you add a default signature at the bottom, make sure it starts below a correct delimiter ("-- ", two dashes and a space), so readers can automatically snip it off when replying.
To keep the mailing list archive small, please upload things like screenshots or SQL dumps to external services and post the link to the list.
No HTML mails
Also to keep the archive small and to ensure a consistent quoting style please untick "HTML mail" in your mail client settings. The good news is you can now use ASCII art! ;)
No ticket discussions
Please use the CC field of a Trac ticket to include people that you would like to get feedback from on a question or solution. Exceptions may be OK for project coordination and to find a person that knows more about a subject. But always supply a link to the ticket and encourage people to reply in a ticket comment instead of an email to the list.
An email following all the rules would look like this: