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"E-Mail Growth Hogs Enterprise Resources"
Source: Network World Magazine, 31-Jan-2000
  • Study of corporate email usage, citing David Ferris, president of Ferris Research;
  • Average number of messages received by end users is expected to jump 81% to 34 per day by the beginning of 2001;
  • Average size of a message is expected to increase 192% to 286 kbytes by the beginning of 2001 [with growth attributable to attachments];
  • There are nearly 170 million corporate email boxes worldwide, more than three times the number of boxes five years ago, according to Eric Arnum, editor of "Messaging Online";
  • There are approximately 440 million corporate and personal mailboxes worldwide

"AOL Per-User Email Figures Climb 60 Percent in 1999"
Source: "Messaging Online," 4-Feb-2000
  • 3.5 messages per AOL user per day in 1998, and 5.6 in 1999;
  • 110 messages sent in 1999, up from 50 million in 1998;
  • 20.5 million users at the end of 1999
  • Email usage per person increased 60 percent in 1999;
  • "If you believe every person in the U.S. has an email account (and it's beginnign to seem that way), then you are talking 1.54 billion messages per day, or 560 billion messages per year. If you believe half the population has email, then your numbers are 770 million messages per day or 280 billion messages per year. Adjust those numbers to reflect heavier usage by the workforce email users and lighter usage by Webmail and ISP users, and you possibly could come up with a trillion messages per year."
  • In 1999, the U.S. Postal Service delivered over 200 billion pieces of mail, so email volume now outpaces postal mail volumes;

"Messaging Today: Worldwide Trends"
Source: "Messaging Online," 14-Mar-2000
  • The total number of electronic mailboxes in the world has soared 83.5 percent in the past year to 569,171,660 mailboxes;
  • In the U.S., the number of mailboxes has jumped 73 percent to 333.5 million mailboxes since the end of 1998. In the rest of the world, the total number of mailboxes has grown 101 percent to 235.6 million mailboxes in the past year;
  • In the U.S., the average corporate email user has around 1.5 mailboxes, and the average household using email has about 4 mailboxes.
  • There are about 89 million Americans using email at work and roughly 50 million households using email
  • There are probably 110 million Americans using email at home or at work, 40 percent of the population.
  • There are fewer than one billion televisions in the world, fewer than 800 million phone lines, and 569.2 million mailboxes;
  • This paper contains other interesting information and graphs. Here are two samples::
Millions of Mailboxes Worldwide
Distribution of Mailboxes Worldwide

24/7 Media: Email Facts
Source: 24/7 Media
  • Opt-in email volume will jump 52.3% to 61.1 billion by year-end 2000, and reach 240 billion messages by 2003.
  • There were 78 million active e-mail users, aged 13 and older, in the U.S. at year-end 1999, accounting for 35% of the total U.S. population of adults and teens (13+)
  • By year-end 2002, there will be 135 million e-mail users, representing 59% of the overall U.S. population of adults and teens. (Source: Emarketer)
  • There were 409 million e-mail boxes worldwide in 1999, up from 234 million a year earlier. In 1999, an estimated 20% of all e-mail received in the U.S. was commercial, split almost evenly between spam and permission e-mail (Source: Emarketer)

Nov. 92 - Nov. 94 - Messages Per Month
Source: Internet Society


# of Messages
Nov. 92 279,060,000
Dec. 92 262,320,000
Jan. 93 286,920,000
Feb. 93 317,616,667
Mar. 93 363,180,000
Apr. 93 352,410,000
May 93 410,700,000
Jun. 93 371,700,000
Jul. 93 383,340,000
Aug. 93 397,860,000
Sep. 93 421,320,000
Oct. 93 479,853,333
Nov. 93 508,980,000
Dec. 93 469,370,000
Jan. 94 516,540,000
Feb. 94 527,170,000
Mar. 94 636,140,000
Apr. 94 695,220,000
May 94 731,220,000
Jun. 94 747,960,000
Jul. 94 765,840,000
Aug. 94 803,100,000
Sep. 94 899,400,000
Oct. 94 1,033,920,000
Nov. 94 1,007,590,000

Junk Email

Other Information
  • has 14.4 million e-mail boxes, which require 27 terabytes of storage.
    Source: Network World, Network Storage White Paper
  • 300 million e-mails are sent per day in the US.
    Source: Thomas Staffing of California
  • Today's users send about 15 messages a day and receive about 20 a day, on average. This colume is expected to grow by some 60% and 80% respectively over the next year.
    Source: Ferris Research
  • Electronic mailboxes will more than double in the next two years to an estimated 112 million in 1999.
    Source: Electronic Mail & Messaging Systems
  • UC Berkeley's average message size in August, 2000 was 18,517 bytes, with median size of 1863 bytes.

Final Thoughts

Based on the information above, 500 to 600 billion email messages in 2000 seems to be a reasonable non-inflated estimate [though it might be lower than the actual number]. While the average size of email message is hard to tell, we can predict the volume of storage needed from the data above. For example, uses 27 terabytes of storage space for its 14.4 million email boxes, and the number of email boxes can be estimated to be between 450 and 500 million. With the average of 475 million email boxes in 2000, the volume of storage needed can be estimated at 900 terabytes, which is lower than the number obtained by multiplying the number of messages by their [probable] average size. The explanation may be that this is the amount of messages stored, not the measure of flow.

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