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Old 12-28-2009, 01:43 PM   #1
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Why do I get "User Unknown" while sending an email


My name is Agustin de Landa and I have a Linux box running Red Hat Enterprise Linux ES release 3 (Taroon Update 9)

I have many users created and using sendmail with SMTP and POP3 services and all of them running OK.

Today I created a new user in the same way we have always done it in the past and for some strange reason this user is not accepted when trying to send an email to it.

We always get: User unknown

The difference I have is that all my users are created with Lower case and this particular one has the fisrt letter in Upper Case and the rest in Lower case.

Could this be the problem?

Thanks in advance.
Old 12-28-2009, 01:53 PM   #2
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Usually e-mail addresses aren't case sensitive. The first things you should do is to double-check the username, and try sending an e-mail with the address in all lower-case.
Old 12-28-2009, 02:24 PM   #3
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I have done the test and the same error.

Old 12-28-2009, 07:58 PM   #4
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Found the problem, it has to do with Upper and Lower case.

I created the user with lowercase letters and it works fine.

So my conclusion is that sendmail for the redhat version I have doesnot support Capital Letters in users.



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