Here is a frequent problem on mailing lists which occurs when people are trying to save a bit of time and (probably unintentionally) are causing difficulties for others.
I’ve pulled out one example not to highlight one particular individual, this is just the most recent example I’ve seen.
Here’s a collapsed thread in one of my Mail.app mailboxes:
So it looks like there’s a pretty active discussion recently about that topic.
But look what happens when I expand that thread to see all the messages under it:
Whoa! That conversation was actually from two months ago, and instead there are about 7 different discussions under one thread.
What happened?
Simple: Someone hit “Reply” to an existing message and changed the Subject: line, rather than creating a New Message.
When you click Reply, your mail program automatically fills in some hidden headers which tell mail programs “This message is related to that message.” Mail programs are supposed to look for those hidden headers not the Subject line when deciding whether messages belong in the same group or not.
Why did this person use Reply instead of New Message? Probably because using Reply automatically filled in the mailing address for the list. However, almost all mail programs will automatically fill in the To: field if you type a few characters of the name, so this isn’t really saving that much effort.
For example, if I want to post to the Entourage mailing list, all I have to do is start typing the word “Entourage” and it will show me potential matches:
which makes New Message almost as easy to use as Reply (especially since you don’t have to delete the old Subject: line).
Using New Message also helps make sure that your message gets read by as many people as possible.
“How?” you ask.
Well, let’s look at the above example again, where the original message was collapsed. Now imagine I’m scanning through unread messages in the mailbox and see a seemingly long discussion about Scheduling Empty Junk Mail. I might decide that the topic doesn’t interest me for whatever reason, so I decide to skip it.
However, I might know the answer to some of the other problems which have been posted to some of the other threads, but I might not ever see those threads unless I specifically look at this one.
So using New Message not only helps people who have mail readers which sort messages the way they are supposed to (*) but it also helps you make sure the most people see the messages you post. It also helps everyone keep separate discussions separate.
(*) I realize that some will argue that mail clients should use the Subject: line, and in fact GMail does (if you hit Reply in GMail and edit the Subject, it automatically deletes those hidden headers so you won’t create the problem discussed above). The fact of the matter is that the guidelines which have been created for people writing mail clients give a certain way of doing things. You can choose to ignore it and do your own thing, but it’s generally friendlier to try to act not just in your own best interest (i.e. “it’s easier for me to just hit reply!”) but in the interest of everyone in the group. No one else in the group benefits from the few seconds that you might save using Reply instead of New Message, and it has the potential to cause problems for many (including some who might have the answer to the question you are asking).
9 times out of 10 when I explain this to someone, they have no idea that this was causing any problems. There was no malicious intent to cause trouble for anyone, they just didn’t know about the way threading works. I wrote this up as an easy pointer for people to read so they can understand what happens and why. After that, it’s up to you.