Topic: Intermittant SMTP Problem

[CMENL]

Running SME Server 7.1 and I have a frustrating problem.  At times incoming mail is being bounced back to the sender with an SMTP error message - usually 503 - Authentication required kind of thing.

As a test, I sent a message to an external account and replied to it.  Earlier today it work fine.  Replying to the same message (same accounts, same location, same computer) now bounces.

Any suggestions?

[shell]

SMTP authentication is (afaik) not enabled by default.  

here is a link explaining how to turn it on -
http://wiki.contribs.org/Email#How_do_I_enable_smtp_authentication_for_users_on_the_internal_network.

perhaps you are using your isp as smtp server - either at client level or at the server.

are you using the same client from the same network for your tests?  if you are and the settings in your client are static then it is strange that you are only getting the fault intermittently.  smtp servers will either enforce a requirement for authentication or it won't.

give me more info if you want more suggestions

[mmccarn]

Multiple MX records could cause this if one of your records points to a machine that doesn't understand your email...

It would be helpful to see the actual bounce message.

[CMENL]

Last night everything was working fine.  I could mail to the server from different accounts on different networks through several ISPs.  No problem.  This morning, everything bounces.  I have little hair left!!

I am not using my ISP as SMTP server.  I am behind a PIX firewall, operating server-only mode.  There are no other computers connected directly to the server.  Our office network uses the same ISP, behind the same firewall, but through a router at a different IP address.  I can connect using pop3 and imap - and send mail externally.  I can send and receive mail internally (i.e., to accounts set up under the domain cmenl.ca on SMEserver).  I can send mail to the world, and on occasion the world can send mail to me.

e-mail retrieval mode is set as Standard (SMTP) and Authentication is set to Allow both SMTP and SSMTP.

[CMENL]

Multiple MX records could cause this if one of your records points to a machine that doesn't understand your email...

It would be helpful to see the actual bounce message.

  There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.

[mmccarn]

Who is out002.iad.hostedmail.net?  Is this your SME, or some other host?

You may want to check your MX records from off-site.  I do this using:

Code: [Select]

nslookup -type=MX <mydomain> 4.2.2.1(This asks 'nslookup' to return the MX data from the DNS server at 4.2.2.1 for <mydomain>)

[CMENL]

to registrar of my domain, but is not one of the nameservers linked to my domain

[CMENL]

Okay, now it is getting really weird.

I have not changed anything, but I can mail to my account at the domain name, but not to the ip address. I just sent a message to the domain address, cc'd to the ip address.  The domain message made it through, the ip address cc bounced.

[pfloor]

Okay, now it is getting really weird.

I have not changed anything, but I can mail to my account at the domain name, but not to the ip address. I just sent a message to the domain address, cc'd to the ip address.  The domain message made it through, the ip address cc bounced.

SME7 will not accept email addressed to user@IPaddress even if user and IPaddress are valid.  This is an anti-spam/anti-relaying measure.  The only valid email to your IP address is as follows:

postmaster@[External-IP-Address]

and the IP must be enclosed in the "[..]" to work.

Note: this may not work if your email client mangles the header/address.  It seems to work with Outlook but I have not had success sending with Horde.

[CMENL]

By the way, I suggest that you ask the moderators to delete this post as soon as convenient so that your IP, DNS and email info is not floating around for too long...

I've looked around for a link to e-mail the moderator and can't seem to find one.  How do I contact him/her/them?

[CharlieBrady]

70.85.153.146 seems to link back to registrar of my domain, but is not one of the nameservers linked to my domain

Clearly it was, at least temporarily.

This is clearly a DNS problem, and has nothing to do with SME server.

[mmccarn]

You might try adding [PLEASE DELETE THIS THREAD] to the beginning of the title, and sending an email to security at contribs dot org with a link to the thread, asking them to delete it.

Otherwise, you & I can go back and edit our own posts to remove all identifiable information.

I suppose an email to moderator at contribs dot org might go somewhere useful, but I don't know.

Did your email start working?

[CMENL]

Everything seems to be working as of now...  we'll see if it lasts!