SMTP authentication not working with POP3 email accounts

Darrell · Joined: 05 Aug 2007 Posts: 2

I have an Exch2k Post SP3 rollup level server that is enabled for POP3 service to roaming laptops. The Virtual SMTP server is configured not to relay mail and is set to relay for authenticated users. I cannot send email through my SMTP connector from any external address - it seems the Outlook XP client is not authenticating with the SMTP server even though the client is configured to do so.

I can assign the external IP address of the client in the Virtual SMTP server and it will relay (however laptop will float to many different IP addresses-won't work). I can open the relay channel to everyone and it will relay (however SMTP queue fills up immediately with relayers-unacceptable). I have configured the Virtual SMTP Server to not allow anonymous access (trying to force the SMTP connection to authenticate) and the a 1709 error reports saying SMTP client did not authenticate before sending mail. Access denied.
I believe the issue is the client is not able to authenticate (or even trying to authenticate) with the SMTP server. Client is setup to require SMTP authentication. I've tried different user/pass combinations to access. No event log is reported for incorrect credentials for any combination.

Please help. Thanks in advance to your help.
Darrell

Archived from group: microsoft>public>exchange2000>protocols

Darrell · Joined: 05 Aug 2007 Posts: 2

The problem was in the Cisco 1721 router which had ip inspect smtp enabled and according to Cisco it cannot handle esmtp. After removing entry I was able to authenticate SMTP externally.

Thanks for the hint.

"Jeff Thibodeau [MS]" wrote:

> Hi Darrell,
>
> From the Exchange server use telnet and open a connection to itself on port
> 25. Type EHLO and view the list of verbs. Makes sure Exchange is
> advertising the Auth verb.
> Do the same from an external client to see if a firewall might be proxying
> the SMTP commands.
>
> If the internal test does not show the Auth commands check out
> http://support.microsoft.com/default.aspx?scid=KB;EN-US;257569
> If the internal testing is good and the external is not check into your
> filewall settings to make sure SMTP is being passed through the firewall
> and not using a proxy type tool.
>
> I hope this helps.
>
>
> Jeff Thibodeau
> Microsoft
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> Thread-Topic: SMTP authentication not working with POP3 email accounts
> thread-index: AcRqIreFecLzeaqlS7+co/nshWY63g==
> X-WBNR-Posting-Host: 65.85.207.50
> From: "=?Utf-8?B?RGFycmVsbA==?="
> Subject: SMTP authentication not working with POP3 email accounts
> Date: Wed, 14 Jul 2004 21:18:01 -0700
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> Newsgroups: microsoft.public.exchange2000.protocols
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> Xref: cpmsftngxa06.phx.gbl microsoft.public.exchange2000.protocols:7431
> X-Tomcat-NG: microsoft.public.exchange2000.protocols
>
> I have an Exch2k Post SP3 rollup level server that is enabled for POP3
> service to roaming laptops. The Virtual SMTP server is configured not to
> relay mail and is set to relay for authenticated users. I cannot send email
> through my SMTP connector from any external address - it seems the Outlook
> XP client is not authenticating with the SMTP server even though the client
> is configured to do so.
>
> I can assign the external IP address of the client in the Virtual SMTP
> server and it will relay (however laptop will float to many different IP
> addresses-won't work). I can open the relay channel to everyone and it will
> relay (however SMTP queue fills up immediately with relayers-unacceptable).
> I have configured the Virtual SMTP Server to not allow anonymous access
> (trying to force the SMTP connection to authenticate) and the a 1709 error
> reports saying SMTP client did not authenticate before sending mail. Access
> denied.
> I believe the issue is the client is not able to authenticate (or even
> trying to authenticate) with the SMTP server. Client is setup to require
> SMTP authentication. I've tried different user/pass combinations to access.
> No event log is reported for incorrect credentials for any combination.
>
> Please help. Thanks in advance to your help.
> Darrell
>

abatie · Joined: 05 Dec 2007 Posts: 2

"Jeff Thibodeau [MS]" wrote:

> Hi Darrell,
>
> From the Exchange server use telnet and open a connection to itself on port
> 25. Type EHLO and view the list of verbs. Makes sure Exchange is
> advertising the Auth verb.

I am a sysadmin at an ISP, and this is a very common problem for us and we'd
*really* like to know how to fix it; as you can see, we *are* advertising
AUTH, and outlook *is* configured for "outgoing server requires
authentication":

13 10 0.2334 (0.2031) S>C application_data
---------------------------------------------------------------
220 vmail01.peak.org ESMTP Postfix
---------------------------------------------------------------
13 11 0.2343 (0.0009) C>S application_data
---------------------------------------------------------------
EHLO xp
---------------------------------------------------------------
13 12 0.2348 (0.0005) S>C application_data
---------------------------------------------------------------
250-vmail01.peak.org
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-AUTH PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
---------------------------------------------------------------
13 13 0.2372 (0.0023) C>S application_data
---------------------------------------------------------------
MAIL FROM:
---------------------------------------------------------------
13 14 0.2381 (0.0008) S>C application_data
---------------------------------------------------------------
250 2.1.0 Ok
---------------------------------------------------------------
13 15 0.2389 (0.0008) C>S application_data
---------------------------------------------------------------
RCPT TO:
---------------------------------------------------------------
13 16 0.2396 (0.0007) S>C application_data
---------------------------------------------------------------
554 5.7.1 : Client host rejected:
Access denied
---------------------------------------------------------------

abatie · Joined: 05 Dec 2007 Posts: 2

> 250-AUTH PLAIN

After some experimentation, I determined that outlook requires the LOGIN
auth mechanism; with PLAIN, it just silently doesn't authenticate, even when
told the server requires it.

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