Does capitalization in E-mail addresses matter at all?

I know it makes a difference in URLs, but I always thought that capitalization was irrelevant as far as E-mail addresses were concerned (i.e., “” = “”). Am I right or wrong?

I have never seen capitalization matter whatsoever. But for all I know there might be some crazy email system somewhere that is case sensitive.

I don’t see anything in the SMTP which requires case-insensitive treatment, nor in POP3. So, I suppose it is possible.

I just sent two emails to one of my other email addresses, one with the first letter capped (“D”), and one with the first letter uncapped (“d”).

Both arrived at the same email address.

The email was an Earthlink address. So it’s not case sensitive for them, at any rate.

You are right. It makes no difference. The fact it matters in URLs is a touchy subject and relates to Unix file systems.

IMHO case sensitivity in most computer related things totally pointless, unintuative and a constant pain in the neck for programmers and web delvelopers everywhere.

Sheesh! :smack: Grammer and spelling, however, is a good thing.

Case sensitivity in most computer related things is totally pointless, unintuative and a constant pain in the neck for programmers and web developers everywhere.

But where would I go to find out that it is pointless, Futile Gesture? I thought it was for sure, but I couldn’t find a thing to support the statement.

The old original Internet RFCs for domain names (“”) is case insensitive. Ditto when email names were added. As for URLS, the domain name prefix is case insensitive, while the trailing directory/file/script name may or may not be depending on the file system of the server. (Unix is case sensitive, MS-Windows isn’t. The latter causes huge headaches, not the former.)

ftg why do you say the case insensitivity causes problems?

There is a point, of course:

  1. Greater number of options when programming. Thus in UNIX, a command letter R and an r could mean two different things.
  2. Better security. If passwords are case-sensitive, it allows the user to capitalize random letters to make them harder to guess.

Of course, to the casual user, these aren’t all that important. But a lot of software (especially on old mainframes) is designed for the programmer’s convenience, not the users.

Well, as long as you’re going to flagellate yourself, I’ll help. :slight_smile:
Sheesh! :smack: Grammar and spelling, however, are good things.

Case sensitivity in most computer related things is totally pointless, unintuitive and a constant pain in the neck for programmers and web developers everywhere.

Anyway, I have always bemoaned case-sensitivity but I’ve used Unix so long I’m sort of used to it and it seems almost normal to me now. Now if only vi had a case-insensitive search. . . .How many times have I done a grep -i to find lines that I couldn’t find with vi. . . . .

Well, first of all, add the following to your .exrc file

set ignorecase

And vi will do case insensitive search. RTFM

Secondly, in tcsh, I have the following in my .tcshrc (or .cshrc if you go that way):

alias igrep “grep -i”

which saves some strokes.

Neither of which should be related to file system case sensitivity in most situations as this deals with file contents. For most file types, case sensitivity in contents is a must.

I like using mixed case in file names. E.g., “MyNewProg.c” for readability. (It follows a good variable naming style in programming.) Note: I never use blanks in file names as that is a cardinal sin worth of damnation. Anyway, I want “MyNewProg.c” to be that name under any listing under any format on any machine. Period.

BTW, I am really “FtG” but it’s so hopeless getting systems to understand that. Sigh.

RFC822: Standard for the Format of ARPA Internet Text Messages. Section 6, Address Specification, shows that the local part (ie. the portion of the address before the ‘@’) must be uninterpreted and case preserved. However, there is nothing to suggest that the destination Mail Transfer Agent can’t fold case when converting the local part to a mailbox.

The BSD mailaddr(7) man page (although non-normative, it’s not written in standardese) states:

So while it is probably true that you can use any case in an email address, you can’t assume this will be so in the general case.

Thank you, John T. Conklin. That was what I suspected.