And how did others find out?
Mostly through other dopers who knew them IRL or to whom they were particularly close - that’s how it happened with Ayesha, Persephone and poopah chalupa, at least, although I wasn’t actively posting when the latter died.
Family members also get in touch with the board sometimes. David Simmons posted up until his last weeks, and family members gave us the final word through his account and on their own.
Since this isn’t a technical question I’m going to take it to MPSIMS, which is where most of those threads have been posted. Goddam but this is sad stuff to read, even not knowing some of the people involved.
OTTOMH
Poopa Chalupa -Died when he was blown off an overpass.
**
Persephone**- Died when she fell in the tub and hit her head. Her husband or ex husband notified a few close friends, several of whom were Dopers.
I know there are more. I can’t recall at this time.
There is also one case of an alleged death, disputed by many.
As we determined in the prior thread from finding her obituary, indecisive1 died from lung cancer. 
Unfortunately, from the tone of his last post here (and absence since then), I believe A.R. Cane may be another Doper that we’ve lost to cancer even though it has not yet been confirmed to my knowledge.
It is sad to think that there are probably missed posters who have died without any of us realizing it.
This is how a friend of mine died a few months ago. 
I have been really scared of this happening to me ever since Cristi died. She was epileptic, by the way, so it’s probable that the hitting her head was as a result of a seizure.
I often think of Cristi this days, as I am back in Michigan, where we became friends. Every day I walk past a church, and only the other day I realized she’d once pointed it out to me as where she’d been married.
She is missed.
Not to be morbid, but how did this happen? Was his car blown off the overpass, or just him?
Seems like he was changing a tire for a stranded motorist.
IIRC He was sitting on the railing of the overpass when a large truck came by.
)(#%^()#^&^&*()$^&
::ahem::
I didn’t meet Poohpah, Aye or David Simmons, but Euty and I had a ball with Persphone in Chicago some years back.
And now I’ve gotta keep myself composed at work.
Aah, yeah sorry punha, I didn’t even think to let you know via LJ or anything .
One of the most helpless and horrifying feelings I’ve ever experienced was trying to track Eutychus down so he didn’t learn via the Boards. (He lives in RI, as do I.)
I miss her.
This post has a link to the news story on poopah’s death. That page is no longer active, but it might possibly be in the archives.
No worries. My brother (Captain Carrot) didn’t tell me about her or David Simmons. In the case of the latter, I found out accidentally.
Would this be it?
http://216.173.246.226/Astories/nov28/bridgedeath.html
Ya nailed it.
My late wife, Barracuda, was not a prolific poster. She died in July of last year.
I’m very sorry to hear that, movingfinger.
Off topic somewhat, but my sister, who is the executrix of my will, has instructions on how to notify the message boards I visit, should I die unexpectedly.
Am I the only one who has a last SDMB post already prepared?