- my internal smtp server cannot deliver email to hotmail.com, sympatico.ca, etc
- Error found when using SMTPDiag utility
Error: Expected "250". Server rejected the sender address. Failed to submit mail to mx3.hotmail.com
Error: Expected "220". Server is not accepting the connection. Failed to submit mail to mx3.hotmail.com
-In the Event Viewer, I found the following message.
"Message delivery to the remote domain"xxx.com" failed for the following
reason. The connection was dropped by the remote host"
smtp server infrastructure:
- 1 IIS SMTP email server at local area network - called "ismtp"
- 1 IIS SMTP email server at DMZ - called "dsmtp"
dns server :
- 3 dns server internal
- 2 dns server at DMZ
- using isp's dns as dns forwarders.
- using T1 line for internet access normally.
- using cable connection as internet access backup.
The "ismtp" is used for outgoing email only, this server do not receive email. It is being used by Fax Server for "fax to email", or the internal webserver which need email delivery functions.
The "ismtp" server cannot send email to hotmail.com, sympatico.ca, and rogers.com etc because of rejected by them. However if I use dSMTP server as a SmartHost for "ismtp", it works.
Currently, I am using NAT for iSMTP server to translate a public ip to the local ip at firewall. I allow any to any from inside network to internet. The iSMTP server is going to internet via a T1 line.
Also, I tested my iSMTP server with the cable connection, the email for hotmail.com can be delivered when using cable. When I plug my iSMTP server to cable connection, a public ip will be leased by my cable company.
I called my T1 line isp to add the reverse lookup name for my iSMTP server at their dns server but still no help.
I can do the reverse dns lookup for my smtp server from internet like the tools
provided in www.dnsstuff.com
1. Why the same server give me different result when it is connecting to different link for internet access, T1 line and Cable.
2. Why the email for hotmail.com can be delivered if using Smarthost?
3. Someone said, I should register my domain name in SPF (Sender Policy Framework) via http://www.openspf.org
to solve this problem but I think that because the email works if I use SmartHost or cable connection, do I need the SPF?
4. I am going to setup my own Exchange 2003 server for sending and receiving email for internal users, I afraid, the same problem still here after setup the Exchange 2003, therefore I must have to overcome this issue before setup the Exchange 2003.
Any idea? thanks!