The two extra L's are actually silent. However, in real life, some people pronounce it with either a very long L sound at the end, or as Joel-l-l-l, enunciating a bunch of separate Ls.
Sometime in 1982, during my junior year of high school, I was given access to an account on UMass Amherst's Cyber mainframe computers, big iron-age scientific computers that took up whole rooms and had that great James-Bond-movie-villain-headquarters look. The account name was BHH0000, and I logged in using my family's Apple 2 Plus computer with 300 baud modem, and started poking around.
Cybers were a whole new world of computers, different from anything I'd yet seen, which were Apple 2 series home computers, and Digital PDP-8 and PDP-11 minicomputers at school.
The Cyber 175 was the largest and oldest of the mainframes there, running an operating system known as NOS. Without getting into details, I first had to figure out how to properly communicate with it (its memory arrangement was to use 6-bit bytes and 60-bit words, and the standard character set used only uppercase letters, thus fitting into the memory scheme using six-bit ascii (instead of the now-universal 8-bit bytes and 8-bit ascii character set). Lowercase letters required a special character set, and still required two bytes per lowercase letter.
Typing "help" did nothing. Typing all kinds of commands similar to Apple or PDP-11 commands did nothing. I had no "cheat sheet" from which to start.
So then I typed the word "mail". Up came the mail program, named "mailer", custom-written at UMass for internal use on the Cyber. Yowza! A breakthrough!
The very first thing that mailer asked for was a nickname by which this new user would be known, which would be permanent. It had to be between 4 and 7 characters long (account names were up to seven characters), and unique in the mail system. Unix machines all default to the name of the account-holder for email purposes, but the account-naming scheme on this antique was a not-terribly-useful seven-digit number for students, and various account names beginning with letters for non-students.
I tried to use "JOEL" (I hadn't yet figured out how to get the Cyber to talk in lowercase). No luck, there already was a Joel in the mail system, so mailer asked me again. I tried "JOELH", but that was taken too, tried a few other random nicknames, all taken. At random, I typed "JOELL", then looked at it again noticed that it looked off-balance, and hit the L key again, spelling "JOELLL". When I hit the return key, of course there wasn't another one, and finally I could get into the rest of the program to see what I could do.
One of the great features of the mailer program was that it had what were called "notesfiles", or publically accessible mailboxes, analagous to a BBS or forum. Some were read-only except to their managers, and were used for system or mailer announcements, and others were public-writeable on various topics. One was named Graffiti, and was a free-for-all no-topic no-restrictions discussion. It was there that I found a crowd of people, and at some point or another, I started signing my letters with "Atrocity Joelll". I stopped using the "Atrocity" part when the Cyber 175 shut down for good, around 1991.
On the Cyber a whole community was flourishing, with about 120 people from the five-college area that includes UMass. In addition to the mail program, people wrote stories and text-adventure games, and communicated via a series of local chat programs, the first named "talk", then "twinkle" (so resource-intensive that it was allowed to run only at night and on weekends), and finally "confer". Though Boston-based, I made friends with lots of UMass Amherst people, and visited a few times, and then moved out there to live for a few years after failing out of my first attempt at college. We hung out online, in the terminal rooms, and had a weekly coffee break in the campus center or at a nearby restaurant.
My first internet mail was sent from the UMass Cyber, after they connected to BITNET, in 1985. BITNET connected to the internet through the University of Wisconsin, and so my first internet address was BHH0000%umass.bitnet@wiscvm.wisc.edu, with the BHH0000 later being replaced by JOELLL.
Since then, I've been joelll on every system that I've had access to, including my current unix accounts, internet access, IRC, MUDs, the long-gone Delphi online service, and the also long-gone Boston-based Argus BBS. Others have used the name, but as far as I can tell, I'm the only joelll in long-term general circulation on the net.