are e-mail addresses "capital" letter sensitive?

I've been expecting to hear from someone since yesterday.
I decided to view their website and there was a link to send an e-mail.
Well, I had their business card and it was an aol.com address. The user name was 3 words, so 3 words at aol.com. The middle word on the business card was in capital letters.
I sent the e-mail from my Hotmail address. Hours go by and no reply,
This person stands to earn a commission for their help on some real estate so I went to my "sent" box to read over the message I sent them.
The "to" box, shows the 3 words but none of the letters are capitalized.
So, I go back to the website and there is a link to send an e-mail. The address shown there is the same three words at aol.com and the first letter in each word is capitallized.

I can not be a pest by calling this person, so I want to know if my e-mail sent to:
wordWORDword@aol.com got delivered, though when I look at my message in my Hotmail "sent folder" it shows that my message went to wordwordword@aol.com.

Are e-maail addresses capital letter sensitive?

I would guess no, since the business card says:
wordWORDword@aol.com
and the website says
WordWordWord@aol.com
and they are the same 3 words, so it seems illogical to have multiple e-mail addresses all with varying capital letters.

I happen to be on a computer which has Windows Mail but I'm not logged in for e-mail and can not. When I clicked on the e-mail address on the person's website, of course Vista tried to open Windows Mail. And though I can not send an e-mail from there, it has the "new message" box open and has the e-mail addres in the box and it is:
WordWordWord@aol.com which matches "exactly" what the website says.

When I sent my message to wordWORDword@aol.com from my hotmail address, why does the sent copy show that the destination was wordwordword@aol.com?


 
LVL 25
nickg5Asked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

MrN1c3Commented:
The domain name part of an email address is case insensitive (i.e. case does not matter). The local mailbox part, however, is case sensitive. The email address ReCipiENt@eXaMPle.cOm is indeed different from recipient@example.com (but it the same as ReCipiENt@example.com).

But Case Typically Does Not Matter

Since the case sensitivity of email addresses can create a lot of confusion, interoperability problems and widespread headaches, it would be foolish to require email addresses to be typed with the correct case. Hardly any email service or ISP does enforce case sensitive email addresses, returning messages whose recipient's email address was not typed correctly (in all upper case, for example).

This means that

    * it does not typically matter what case you type an email address in when you send a message
          o (If the recipient did give you an email address with distinct case, preserve it, however.)
    * and you should always only use lower case characters when creating a new email address to rule out any confusion.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
MrN1c3Commented:
For further clarification check out RFC2821 section 2.4
0
nickg5Author Commented:
The email address ReCipiENt@eXaMPle.cOm is indeed different from recipient@example.com (but it the same as ReCipiENt@example.com).

but my question is:
is
ReCipiENt@eXaMPle.cOm
the same as
recipient@eXaMPle.cOm
0
Become a CompTIA Certified Healthcare IT Tech

This course will help prep you to earn the CompTIA Healthcare IT Technician certification showing that you have the knowledge and skills needed to succeed in installing, managing, and troubleshooting IT systems in medical and clinical settings.

MrN1c3Commented:
no ReCipiENt@eXaMPle.cOm is not the same as recipient@eXaMPle.cOm

But in reality, whichever one you email will work.  The only exception is where the mail administrators do not conform to the RFC2821 Standard
0
nickg5Author Commented:
so you think my message did get delivered..........

and they are just busy or out of the office or tending to deals that give them larger commissions than mine.........
0
nickg5Author Commented:
It's a real estate agent.
the website says:
WordWordWord at aol dot com.
and the business card says
wordWORDword at aol dot com


and my hotmail says it was sent to wordwordword at aol dot com though I typed it as seen above.
0
MrN1c3Commented:
I would certainly expect AOL to conform to internet standards, so yes, your mail will get deleivered
0
sjohnson4812Commented:
Case sensetivity is not a concern, if it were you would have expected to receive an "Undeliverable Notification" from the recipient mail server. If you have not received a notification, which generally is very quick, then it was accepted and forwarded to the recipient mailbox. You can however send another messge with tracking and delivery reciept notification enabled.
0
nickg5Author Commented:
You can however send another messge with tracking and delivery reciept notification enabled.

from Hotmail?

adding points........
0
sjohnson4812Commented:
I am not sure how Hotmail is setup, perhaps you can but I would not have that answer.
0
MrN1c3Commented:
It looks as if wordwordword@aol.com is an invalid email address.

See below;


MX records for AOL are;

15      mailin-01.mx.aol.com      64.12.222.197      60 min      SMTP Test      Blacklist Check
15      mailin-02.mx.aol.com      205.188.190.1      60 min      SMTP Test      Blacklist Check
15      mailin-03.mx.aol.com      64.12.90.97      60 min      SMTP Test      Blacklist Check
15      mailin-04.mx.aol.com      205.188.103.2      60 min      SMTP Test      Blacklist Check


Test mail to wordWORDword@aol.com & wordWORDword@aol.com Fails, with the same error.
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Resolving hostname...
Connecting...
SMTP -> FROM SERVER:
220-mtain-mi03.r1000.mx.aol.com ESMTP Internet Inbound
220-AOL and its affiliated companies do not
220-authorize the use of its proprietary computers and computer
220-networks to accept, transmit, or distribute unsolicited bulk
220-e-mail sent from the internet.
220-Effective immediately:
220-AOL may no longer accept connections from IP addresses
220 which no do not have reverse-DNS (PTR records) assigned.
SMTP -> FROM SERVER:
250-mtain-mi03.r1000.mx.aol.com
250 DSN
MAIL FROM: me@me.com
SMTP -> FROM SERVER:
250 2.1.0 Ok
RCPT TO: wordWORDword@aol.com
SMTP -> FROM SERVER:
550 5.1.1 : Recipient address rejected: aol.com
SMTP -> ERROR: RCPT not accepted from server: 550 5.1.1 : Recipient address rejected: aol.com

Message sending failed.


XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Now sending a test to dave@aol.com whoever he is :-)    

Works fine!
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Resolving hostname...
Connecting...
SMTP -> FROM SERVER:
220-mtain-mi01.r1000.mx.aol.com ESMTP Internet Inbound
220-AOL and its affiliated companies do not
220-authorize the use of its proprietary computers and computer
220-networks to accept, transmit, or distribute unsolicited bulk
220-e-mail sent from the internet.
220-Effective immediately:
220-AOL may no longer accept connections from IP addresses
220 which no do not have reverse-DNS (PTR records) assigned.
SMTP -> FROM SERVER:
250-mtain-mi01.r1000.mx.aol.com
250 DSN
MAIL FROM: test@test.com
SMTP -> FROM SERVER:
250 2.1.0 Ok
RCPT TO: dave@aol.com
SMTP -> FROM SERVER:
250 2.1.5 Ok
Sending Mail Message Body...
SMTP -> FROM SERVER:
354 End data with .
SMTP -> FROM SERVER:
250 2.0.0 Ok: queued as F17EC380000BC
Message completed successfully.

0
nickg5Author Commented:
just called the lady and she got it.............
so in her case

wordWORDword and WordWordWord both work.........
0
Tiras25Commented:
Usually, email addresses are not case-sensitive.

But increasingly often, mail servers are making a distinction between upper and lower case letters. So you can have mail@mail.com and Mail@mail.com go to two different people.

I'm not sure, but I think some old versions email clients automatically make all the letters lower case. Make sure you have an up to date mail client, and check out the preferences/options/etc sections to see if you can adjust how it handles the case sensitivity on email addresses.
0
nickg5Author Commented:
Hotmail is pretty quick to send a bad one back. Alot faster than OE thru my ISP.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Internet / Email Software

From novice to tech pro — start learning today.