It has sort of always been a habit to put it in there. The point of it is that since a PS appears below the signing this, as Patrik already explained, clarifies that the PS was written by the same person. Postscripts are, as a rule, written by the same person who wrote the rest of the letter/message. Why call out the (overwhelmingly) commonest case for special treatment? It is postscripts written by someone _else_ that need to be flagged. In printed material, it is customary to indicate material written by someone else by putting their role [Ed] or their initials [D.S., for example] there; so to me, putting "DS" at the end of a postscript could only mean that the postscript was written by someone with initials "DS" who HADN'T written the body of the message.

In a message written in English, abbreviations other than English or Latin ones are bound to confuse people rather than "clarify" anything.

Another thing - what kind of mailinglist greetings do you use?

As a native speaker of English, I find "greetings" out of place in messages sent to mailing lists. If one _must_ have such a thing, what's wrong with "Dear readers" or "Dear Squeakers"?

Dan uses the "Hi folks!" greeting which is neutral in gender etc.

It is perhaps a little too informal and culture-bound. Imagine a stranger coming up to you and saying "Hey, cuzzie!".

I often like to write "Hi guys!" but somehow (even if it isn't gender specific in speech nowadays - I have been told) in writing it does seem to imply males to me. Or does it? Would it be "kosher" to use that?

"guys" may be gender-neutral, but "guy" is not. Guy is a man's name. In fact, in a few days' time we here will be celebrating the most famous Guy of all time, although perhaps the Americans will criticise us for remembering a terrorist.

However, the word "guy" has some rather unfortunate connotations.

1. A "guy" is "a rope, chain, rod, or wire attached to something as a brace or guide", hence "to guy something" is "to steady, or reinforce with a guy".

"Hi, ropes"?

2. A "guy" is an effigy displayed and burned as part of November 5th celebrations.

"Hi, soon-to-be-burned effigies"?

3. To "guy" someone is "to make fun of" or "ridicule" them. Hence a "guy" is the butt of ridicule.

"Hi, dumbos"?

4. A "guy" can be "a person of grotesque appearance". It's not clear to me that this is really different from sense 3.

"Hi, freaks"?

5. A "guy" can be "a man or boy (an informal use)".

6. "In informal *American* English, you can address a group of people as guys or you guys, whether they are male or female."

7. A "fall guy" can be the victim of a deception or a scapegoat; typically made a scapegoat by means of a deception.

"Hi, dupes"?

As a homebrewed variant I have been using "Hi all!" but it limps a bit (might be a Swedish saying). :-)

While pointless, it is at least inoffensive.

After checking around it also seems that most people think it should be "PPS" as in "post post scriptum". But somewhere I saw that it could mean "post scriptum secundum". He. www.webster.com "Etymology: New Latin 'post postscriptum'. An additional postscript." Of course, in e-mail we are at liberty to fold our postscripts back into the body of the text without tearing up any pages or re-penning anything...