Results 1 to 5 of 5
  1. #1
    Platinum Lounger
    Join Date
    Jan 2001
    Location
    Quedgeley, Gloucester, England
    Posts
    5,333
    Thanks
    0
    Thanked 1 Time in 1 Post

    What's the maximum length of an email address?

    Not really sure which forum to post this in, but this looks probable!

    I wonder whether anyone knows the definitive answer to the question: what is the maximum length of an email address, such as <font color=blue>verylongpersonname@verylongdomainname.c o.uk</font color=blue>.

    This is probably really two separate questions, in two different areas:
    1. <LI>what is the maximum length of the person's name, before the @?
      <LI>what is the maximum length of a domain name? (I assume the .co.uk or .com or whatever is not included)
    A response from anyone who knows what the relevant Standard(s) say(s) would be appreciated!

    Of course not everyone follows standards, or perhaps sets their own, so there may be some form of implementation restriction, but I would have thought that sinc emessages are carried over all implementations of mailservers there must at least be a consensus view?
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

  2. #2
    Plutonium Lounger Leif's Avatar
    Join Date
    Dec 2000
    Location
    U.K.
    Posts
    14,010
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: What's the maximum length of an email address?

    The 'standards' I have heard about are referred to as "RFC" standards - but Googling on that brings up quite a few pages <img src=/S/grin.gif border=0 alt=grin width=15 height=15>

    A couple of pages I did find, although nothing conclusive:
    phpbuilder.com message board
    and
    RFC Editor.

    Good luck!

    ************************
    Edited to add:

    I think specificall RFC-822 covers such matters.

  3. #3
    Platinum Lounger
    Join Date
    Jan 2001
    Location
    Quedgeley, Gloucester, England
    Posts
    5,333
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: What's the maximum length of an email address?

    Leif

    I also did a bit of Googling later and found
    * from RFC2821, about SMTP, that the maximum name length is 64, and the maximum domain name length is 255 (assuming I understood it right)
    * from a "buy your own domain" website that the maximum domain name length was 64, including the .co.uk, .com, .ac.uk, etc

    I presume that the RFC2821 is the "definitive standard" for mail -- but could there be implementation restrictions somewhere in the world?
    And the "buy your own domain" website said not to blame them because they didn't make the rules -- but didn't say who did!

    Edited later to add...

    Nominet, which deals with most .uk registrations, has a "good luck in your hunt" website, from which I eventually find that that the maximum length of a domain name as in "ukdomainname.co.uk" is indeed 64, although they are intending to let the third-level part (the "ukdomainname") be as long as 63 characters, some time in the future. So it seems clear that the maximum length is, to some extent at least, "country domain-registration-authority"-defined, but probably at 64 characters or greater.

    And as far as I can see, in the UK your domain name can contain only a-z, 0-9 and -. But I'm sure I've seen domain names containing capital letters?

    <big><font color=blue>"I love standards - so many to choose from!"</font color=blue></big>
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

  4. #4
    Plutonium Lounger Leif's Avatar
    Join Date
    Dec 2000
    Location
    U.K.
    Posts
    14,010
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: What's the maximum length of an email address?

    I believe that email addresses and domain names are case insensitive, thus

    http://www.wopr.com is the same as http://WWW.WOPR.COM

    I suspect that domain names are written with capitals, simply to make them more memorable and legible. Driving behind a bus and seeing an ad for www.<big>J</big>ohn<big>G</big>ray.com is easier to read than www.johngray.com.

  5. #5
    Platinum Lounger
    Join Date
    Jan 2001
    Location
    Quedgeley, Gloucester, England
    Posts
    5,333
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: What's the maximum length of an email address?

    Leif

    I agree (mostly) with you, because the USER can specify either an email address or a domain name in mixed case, and "it works", presumably because it is interpreted as the equivalent lower-case form, in which it was originally set up/defined.

    But I wonder what would happen if the domain names on the main DNS servers could be specified in MiXeD CaSe? Giving you the possibility of WoPr.com, WOPr.com and so on as different domain names. I suspect that "bright idea" was scrubbed in 1982 or so as a Dilbert-style Management "Doh" Suggestion...
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •