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Error 550 in Outlook / Express: 'Authentication required for relay'.

We have the following settings:

Allow Relay: Nobody
Bypass relay settings when using SMTP authentication: checked
Require SMTP Authentication: Checked
In Outlook - 'My server requires authentication': checked.

The only way we can send email from Outlook is to switch off 'Require SMTP Authentication' and select 'Local Users' for the 'Allow Relay' settings, which is obviously not a great idea.

 Any suggestions?

 Set smtp logging to detailed and look at your logs to see if outlook is authenticating. It should look like:

13:21:55 [xxx.xxx.xxx.xxx][27568327] rsp: 220 mail.yourdomain.com
13:21:55 [xxx.xxx.xxx.xxx][27568327] connected at 5/6/2008 1:21:55 PM
13:21:55 [xxx.xxx.xxx.xxx][27568327] cmd: EHLO [127.0.0.1]
13:21:55 [xxx.xxx.xxx.xxx][27568327] rsp: 250-mail.yourdomain.com Hello [xxx.xxx.xxx.xxx] 250-SIZE 250-AUTH CRAM-MD5 250 OK
13:21:55 [xxx.xxx.xxx.xxx][27568327] cmd: AUTH CRAM-MD5
13:21:55 [xxx.xxx.xxx.xxx][27568327] rsp: 334 xxxxxxxxxxxxxxxxxxxxxxxx
13:21:55 [xxx.xxx.xxx.xxx][27568327] rsp: 235 Authentication successful
13:21:55 [xxx.xxx.xxx.xxx][27568327] Authenticated as user@yourdomain.com
13:21:55 [xxx.xxx.xxx.xxx][27568327] cmd: MAIL FROM:<user@yourdomain.com> SIZE=2209

Here is the output from my logs:

22:33:16 [my_ip_address][58823624] rsp: 220 [server_name]
22:33:16 [my_ip_address][58823624] connected at 06/05/2008 22:33:16
22:33:16 [my_ip_address][58823624] cmd: XXXX Desktop01
22:33:16 [my_ip_address][58823624] rsp: 500 command unrecognized
22:33:16 [my_ip_address][58823624] cmd: HELO Desktop01
22:33:16 [my_ip_address][58823624] rsp: 250 [server_name] Hello [my_ip_address]
22:33:16 [my_ip_address][58823624] cmd: MAIL FROM: <[my_email_address]>
22:33:16 [my_ip_address][58823624] rsp: 250 OK <[my_email_address]> Sender ok
22:33:16 [my_ip_address][58823624] cmd: RCPT TO: <[to_email_address]>
22:33:16 [my_ip_address][58823624] rsp: 550 <[to_email_address]> No such user here
22:33:16 [my_ip_address][58823624] cmd: QUIT
22:33:16 [my_ip_address][58823624] rsp: 221 Service closing transmission channel
22:33:16 [my_ip_address][58823624] disconnected at 06/05/2008 22:33:16

The only email addresses that can be sent to are those hosted on the same server. Receiving mail in Outlook works fine.

 It looks like your outlook isn't even trying to authenticate. I'd double check the settings in outlook, and maybe try a different client to see how it behaves. The first thing your client should try after recieveing 250 hello is auth something, I think.

 I have tried in both Outlook and Outlook Express - from 2 locations. There aren't really a lot of options to get wrong in either. I agree that the SMTP authentication just doesn't seem to be working - hence only emails to the local users can be sent.

Is there a service somewhere that may not be started, or perhaps something wrong with the SM internal SMTP server.....

I get the same thing with outlook express. I don't use it, so I'm not familiar. Try a different client, then you know which way to troubleshoot.

You are using a Cisco Pix firewall. It is preventing the SMTP Authentication from occuring.

Take a look at this article here: http://www.eudora.com/techsupport/kb/2539hq.html

YES!

That was it. Thanks a lot.

Flapjack:

22:33:16 [my_ip_address][58823624] rsp: 220 [server_name]
22:33:16 [my_ip_address][58823624] connected at 06/05/2008 22:33:16
22:33:16 [my_ip_address][58823624] cmd: XXXX Desktop01
22:33:16 [my_ip_address][58823624] rsp: 500 command unrecognized
22:33:16 [my_ip_address][58823624] cmd: HELO Desktop01
22:33:16 [my_ip_address][58823624] rsp: 250 [server_name] Hello [81.6.201.220]

 

In case anyone is curious how I knew he was using a Cisco Pix, the bold line is the tell. It replaces EHLO with XXXX to trick the client into thinking that extended SMTP commands are not supported (i.e. authentication).