# email addresses **URL:** \ **Category:** Factual Questions\ **Created:** [January 18, 2007, 2:29pm UTC](https://boards.straightdope.com/t/email-addresses/388448 "2007-01-18T14:29:24Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Queuing](https://avatars.discourse-cdn.com/v4/letter/q/90ced4/32.png) [@Queuing](https://boards.straightdope.com/u/Queuing)\ **Post date:** [January 18, 2007, 2:29pm UTC](https://boards.straightdope.com/t/email-addresses/388448/1 "2007-01-18T14:29:24Z")
Why are email addresses always in lower case? I always thought that anything in front of the domain name was NOT case sensitive, is this true? Or am I wrong? Thanks. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [January 18, 2007, 2:41pm UTC](https://boards.straightdope.com/t/email-addresses/388448/2 "2007-01-18T14:41:02Z")
It’s not. But what that means is that the server will treat MYEMAIL the same as myemail or MyEmail. You can put the caps wherever helps you remember it better, the server will store it as myemail. ---
**Author:** ![Queuing](https://avatars.discourse-cdn.com/v4/letter/q/90ced4/32.png) [@Queuing](https://boards.straightdope.com/u/Queuing)\ **Post date:** [January 18, 2007, 2:49pm UTC](https://boards.straightdope.com/t/email-addresses/388448/3 "2007-01-18T14:49:57Z")
What if the primary SMTP email address is entered with capitalized first letters? [Queuing@company.com](mailto:Queuing@company.com) instead of [queuing@company.com](mailto:queuing@company.com)? ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [January 18, 2007, 2:52pm UTC](https://boards.straightdope.com/t/email-addresses/388448/4 "2007-01-18T14:52:34Z")
I think the reason for using lower case in simply that UPPER CASE IS IRRITATING TO READ ALL THE TIME. The general convention all over the internet is that using capital letters is rude–it’s like shouting at the top of your voice. which would you rather get a nice happy-brithday message from : yourgrandmother @ [superserver.com](http://superserver.com) or YOURGRANDMOTHER @ [SUPERSERVER.COM](http://SUPERSERVER.COM) ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [January 18, 2007, 3:07pm UTC](https://boards.straightdope.com/t/email-addresses/388448/5 "2007-01-18T15:07:22Z")
[QUOTE=Queuing] What if the primary SMTP email address is entered with capitalized first letters? [Queuing@company.com](mailto:Queuing@company.com) instead of [queuing@company.com](mailto:queuing@company.com)? [/QUOTE] The servers will interpret both of those as being identical. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2007, 3:13pm UTC](https://boards.straightdope.com/t/email-addresses/388448/6 "2007-01-18T15:13:14Z")
How about emails at a subdomain? [mangetout@xyz.company.com](mailto:mangetout@xyz.company.com) could be different from [mangetout@XYZ.company.com](mailto:mangetout@XYZ.company.com), couldn’t it? ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [January 18, 2007, 3:22pm UTC](https://boards.straightdope.com/t/email-addresses/388448/7 "2007-01-18T15:22:56Z")
[QUOTE=Mangetout] How about emails at a subdomain? [mangetout@xyz.company.com](mailto:mangetout@xyz.company.com) could be different from [mangetout@XYZ.company.com](mailto:mangetout@XYZ.company.com), couldn’t it? [/QUOTE] Nope. I just tried with my university email address; [dervorin@DePaRtMeNt.school.ac.uk](mailto:dervorin@DePaRtMeNt.school.ac.uk) got delivered with no problems. ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [January 18, 2007, 3:27pm UTC](https://boards.straightdope.com/t/email-addresses/388448/8 "2007-01-18T15:27:28Z")
[QUOTE=chappachula] which would you rather get a nice happy-brithday message from : yourgrandmother @ [superserver.com](http://superserver.com) or YOURGRANDMOTHER @ [SUPERSERVER.COM](http://SUPERSERVER.COM) [/QUOTE] Neither of those. My choice would be: YourGrandmother @ [SuperServer.com](http://SuperServer.com) Using upper case at the beginning of each word makes it much easier to read, especially when the same letter occurs twice in a row, or when consecutive words form words that really aren’t there. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2007, 3:27pm UTC](https://boards.straightdope.com/t/email-addresses/388448/9 "2007-01-18T15:27:40Z")
I think you’re right - I was going to say that I thought it might depend on how the traffic was handled, but it looks as though there really isn’t any such thing as case sensitivity in DNS lookups. I know some web servers are case sensitive, so [www.company.com/xyz/file.txt](http://www.company.com/xyz/file.txt) might be different from [www.company.com/XYZ/File.txt](http://www.company.com/XYZ/File.txt), but that’s a wholly different thing from the way traffic is routed to email servers. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [January 18, 2007, 3:30pm UTC](https://boards.straightdope.com/t/email-addresses/388448/10 "2007-01-18T15:30:59Z")
To recap, no version of these questions are case sensitive. e-mails and web addresses all work just fine in whatever case(s) you want to put them in. ---
**Author:** ![corkboard](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@corkboard](https://boards.straightdope.com/u/corkboard)\ **Post date:** [January 18, 2007, 3:38pm UTC](https://boards.straightdope.com/t/email-addresses/388448/11 "2007-01-18T15:38:35Z")
I’m always amused when people give me their email addresses and specifically tell me which letters should be capitalized (“it’s [johnsmith@fakecorp.com](mailto:johnsmith@fakecorp.com), but make sure you type capital J, lower case o-h-n, capital S, lowercase m-i-t-h”, etc). I usually purposely screw it up just to mess with them. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2007, 3:43pm UTC](https://boards.straightdope.com/t/email-addresses/388448/12 "2007-01-18T15:43:19Z")
[QUOTE=Shagnasty] To recap, no version of these questions are case sensitive. e-mails and web addresses all work just fine in whatever case(s) you want to put them in. [/QUOTE] Not so. Web addresses (or at least folders and files on web servers) can be case sensitive, if the web server is configured that way. example: [www.gurman.co.uk/test/test.txt](http://www.gurman.co.uk/test/test.txt) [www.gurman.co.uk/test/Test.txt](http://www.gurman.co.uk/test/Test.txt) Domain names themselves aren’t case sensitive, though. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2007, 3:44pm UTC](https://boards.straightdope.com/t/email-addresses/388448/13 "2007-01-18T15:44:25Z")
Agh… fouled up my own links… try again; THESE are different: [www.gurman.co.uk/test/test.txt](http://www.gurman.co.uk/test/test.txt) [www.gurman.co.uk/Test/test.txt](http://www.gurman.co.uk/Test/test.txt) ---
**Author:** ![Queuing](https://avatars.discourse-cdn.com/v4/letter/q/90ced4/32.png) [@Queuing](https://boards.straightdope.com/u/Queuing)\ **Post date:** [January 18, 2007, 3:45pm UTC](https://boards.straightdope.com/t/email-addresses/388448/14 "2007-01-18T15:45:52Z")
Thanks, that is what I thought. It is my understanding that domain names are not case sensitive but anything after them can be, but aren’t necessarily. This seems to be what is being said here. Thanks. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2007, 3:48pm UTC](https://boards.straightdope.com/t/email-addresses/388448/15 "2007-01-18T15:48:31Z")
I suppose someone could actually develop a mail server application that was case sensitive, so that [Joe@bloggs.com](mailto:Joe@bloggs.com) would be different from [joe@bloggs.com](mailto:joe@bloggs.com), but it’s hard to imagine why anyone would bother. ---
**Author:** ![nesta](https://avatars.discourse-cdn.com/v4/letter/n/a4c791/32.png) [@nesta](https://boards.straightdope.com/u/nesta)\ **Post date:** [January 18, 2007, 10:29pm UTC](https://boards.straightdope.com/t/email-addresses/388448/16 "2007-01-18T22:29:35Z")
Using the SMTP protocol, which is what is used to transfer email over the internet, the local part of the address (before the @) is case sensitive, but the domain (after the @) is not. This is outlined in [RFC 2821, section 2.4](http://tools.ietf.org/html/rfc2821.html#section-2.4). It says: > [@](#): > > The local-part of a mailbox MUST BE treated as case sensitive. Therefore, SMTP implementations MUST take care to preserve the case of mailbox local-parts. Mailbox domains are not case sensitive. In particular, for some hosts the user “smith” is different from the user “Smith”. However, exploiting the case sensitivity of mailbox local-parts impedes interoperability and is discouraged. So technically email addresses are case sensitive, but using this functionality is discouraged to avoid confusion. A little more email address trivia from that RFC: the maximum local-part length is 64 characters, and the maximum domain length is 255 characters, so the longest email address you can have and still be within spec is 320 characters. Now that would be a hard address to remember or spell out over the phone.