Can't get e-mail via POP3 Exchange 2010

zer0zer0 used Ask the Experts™
I'm trying to set up a new exchange server and have everything configured to send e-mail and receive through outlook web access and standard exchange access.  However I can't get the email through POP3.  I've enabled the service, added firewall rules.

If I set up the account in outlook for POP3 access and do the "Test Account Settings"
"Log onto incoming mail server (POP3)" shows as completed as if it works.

Once I close this, and do a send/receive I get the following error.

Task ' - Receiving' reported error (0x800CCC90) : 'Your incoming (POP3) e-mail server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: -ERR Server Unavailable. 21'
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Do you have the pop3 connector set to require ssl or tls?
cpmcomputersManaging Director

Pop3 on exchange 2010 does not allow basic password connections by default
You can change it but it is considered a security risk

To prove if this is your problem
If you telnet the server internally
Ie telnet serverip 110
You will get a message server not available in this state error


I get the following
+OK The Microsoft Exchange POP3 service is ready.

If I hit enter, I get "-ERR PROTOCOL ERROR. 17"
If I hit enter again, I get "-ERR PROTOCOL ERROR 19"
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cpmcomputersManaging Director

ok try it again

then follow it with

user avalidusername <enter>
it should respond +ok

pass validuserspassword <enter>
it should respond +ok User successfully logged on

It should respond with a list of email stats

It should respond
+OK signing off
connection to host lost

How are your clients connecting to the exchange server ?
External to the network or internally?


Ok I tried that.  I do get +OK for the username, but it's giving me a password error.  My password is 100% correct though.
cpmcomputersManaging Director

Interesting? error (0x800CCC90) refers to invalid credentials usually username and/or password?

What format are you using for the username and password
Can you post the exact error message it gives.

meanwhile I will check to see if this could be related to anything else?


I just tried it again and it worked..  Hmm.. Still cant get e-mail from POP3 in outlook though.
I got an error 17 even after typing the username the same both times.
I added my account info into GMail so it would pull it into my normal account and I get this error in gmail while trying to recieve from POP3.

"Error: Server is temporarily unavailable.
Server returned error "Error in RETR command: Server Unavailable. 21" "

Here's the Telnet log.

+OK The Microsoft Exchange POP3 service is ready.
user jh******p
-ERR Protocol error. 17
user jh******p
pass ********
+OK User successfully logged on.
+OK 19 25229
1 1606
2 1721
3 4757
4 4744
5 827
6 827
7 827
8 829
9 829
10 827
11 827
12 829
13 829
14 829
15 829
16 826
17 822
18 822
19 822
cpmcomputersManaging Director

Can you check your server configuration in exchange 2010 under the pop3 properties
Authentication tab and ensure the top option (basic authentication) is set If not set it and restart the pop3 service and retest

One other thing check the user account in AD is not set to "user must change password at next login"

What operating system is on this server ? btw?


Options were already set like you said they should be.  It's Server 2008.
cpmcomputersManaging Director

What are you using for a telnet client
Just a command prompt or something like putty ?

Have you got all the latest service packs/roll ups installed (server will need to be rebooted)

Is this the only exchange server on the network ?


This is the only exchange server on the network and I was using putty.
Managing Director
Try from a simple command prompt it seems there is a known issue with putty and exchange 2010

Is your internal domain in the format
mydomain.local or my

I take it that it is added as an accepted domain (authoritative) in your organisation config in exchange

Sorry to keep asking random questions but I am trying to built a picture of what is happening here

The objective is to ensure we can get a clean  
pop3 connection via telnet locally


I had it in as an accepted domain, but the .local was set as the default.  I toggled the .net (the actual email address) and it started downloading right away.  If I set the .local to default - it still downloads all the e-mail now.  Not sure why it works both ways, but it's working and I'm happy!  Thank you for all the help!
cpmcomputersManaging Director

That was the line I was going down
Delighted it works (assuming no "knock on " 
I suspect if the domains had been left unaltered then entering the username as would have had the same effect ?  ( perhaps another expert could advise ?)

Maybe its me being pedantic but I like to fully understand the underlying principle here (hopefully to help others in the future)
Great result all the same :-)


I tried every username format you can imagine.
cpmcomputersManaging Director

Glad you have a result
No rush, but if you do a telnet test now with putty do you get a clean pop3 session
How does this differ with a command prompt session ?

Other than that let's close this and see if anyone can offer an explanation :-)


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