Can't Send Mail SBS 2003 R2

[tapicomms]

Hi All
Have a hell of a problem, changed ISP last week now on the exchange server i can recieve mail but sending mail just sits in the queue and retries till it timeout.
The SMTP Connector has the error, The connection was dropped by the remote host.
I have tried changeing the delivery to smarthost but get the mail retrying to send.

I have run the smtpdiag.exe and it passes all tests, i have run have telnet from the server on to the mail servers and can get a reply.

I have looked at the log file for the smtp connection and it seems that it is sending read reciepts and ndr's.

Can anyone throw some light on this

Glen

 

[thalligan]

Check to make sure the new ISP is not blocking outgoing SMTP traffic (Some do, but usally not business clients or Static IP's)

I assume you are using a Smarthost that has been configured to accept mail from your network.

 

[tapicomms]

Hi thalligan

yes i can telnet on port 25 to other smtp servers and get a reply.
I am using DNS to deliver mail, have tried isp's smtp server as smarthost but same issue
NDR's & Read Reciepts are being sent

 

[thalligan]

Do you have reverse DNS setup on the new IP?

 

[tapicomms]

Do you mean reverse DNS on my new ISP or on my internal DNS server

 

[thalligan]

Also the ISP smarthost may use SMTP auth if you smarthost off of it. So you would need to setup Outbound Auth. Verizion does this so maybe you provider does also. Check with your ISP for Smarthost availbility and usage.

 

[thalligan]

Some servers will not accept email from systems without proper PTR records setup. ie mail.whatever.com --> xxx.xxx.xxx.xxx

and xxx.xxx.xxx.xxx --> mail.whatever.com. This probably is not your issue if none of your mail is leaving the queue, but should be taken care of.

 

[ShackDaddy]

Sounds like outbound port 25 may be blocked which is often the default when you first get set up on a new DSL line.

ShackDaddy
Shackelford Consulting

 

[tapicomms]

I am NOT using smarthost for email delivery, i did try using smarthost but i got the same issue.

i will check the PTR records on my DNS server

Port 25 can't be blocked because i can telnet on to other smtp servers and get a reply

 

[ShackDaddy]

Don't worry about the PTR on your server. Your new ISP has to set you up an RDNS/PTR record for their public network. Every month more and more remote domains are doing RDNS verification and I wouldn't be surprised if this was your problem. Call them and ask them to create the record for you.

ShackDaddy
Shackelford Consulting

 

[thalligan]

1. Check for the use of external DNS servers in the SMTP connector properties. It has been a while but I recall a client having these set to DNS servers that could no longer be reached and this caused issues.

2. Take the time to verify what you think is true from your ISP re SMTP traffic and configuration of Smarthost. It can't hurt.

3. Jack up SMTP logging on your system send test messages and see what your server is saying the issue is.