Several months ago one of our users got a virus that ended up getting our email blacklisted. I got the virus cleaned up and requested to be removed from the blacklists. I created a routing group connector through Dyndns to route emails that I could still would not go through. Things are finally somewhat back to normal. However, it seems that we are still receiving more NDRs on a daily basis than I am comfortable with. They are not consistent as far as who is sending or receiving and one that doesnt get delivered today may work tomorrow. A few of the NDRs received are as follows:
Could not deliver the message in the time limit specified. Please retry or contact your administrator.
The e-mail system was unable to deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system administrator.<mail.ourcompany.com #4.0.0 smtp;451 Temporary local problem - please try later>
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator. <mail.ourcompany.com #5.5.0 smtp;550-Callout verification failed:>
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator. <mail.ourcompany.com #5.5.0 smtp;550 Sender verify failed>.
Also in the Event viewer I am receiving mutiple Event IDs 7004. This is an SMTP protocol error log for virtual server ID1, connectuion #3. The remote host "external ip address", responded to the SMTP command "xexch50" with "504 Need to authenticate first". The full command sent was "XEXCH50 2552 2". this will probably cause the connection to fail.
I dont recall having so many NDRS and errors in the event log prior to the virus/blacklisting issue. I have been researching this for so long and cannot figure it out. I am pulling my hair out and soon the users are going to lose their patience. Any help at all would be greatly appreciated.
We are running Exchange 2003 on Server 2003.
Thank you in advance for any help that you may give.