Our organization recently switched ISPs. We got a new data T1 and new IP addresses from AT&T. I've switched our A record tat our registrar to point to the new WAN IP for our exchange server. Everything seems to work, but here's the problem:
Most email goes out from our organization. I tested several high level domains: gmail.com, yahoo.com, but there are a few other domains that I cannot send email to.
When I try and send mail to a comcast.net, agfc.state.ar.us, or several other domains, we get a delay of delivery notification from our exchange server.
Our exchange server is not set up as a mail relay, our SMTP virtual outbound settings do not point to a smart host. We are managing everything from our exchange server
There are hundreds of application event warnings for the MSexchangeTransport in our event logs. Here are a few examples:
Category: SMTP Protocol
Event ID: 7010
This is an SMTP protocol log for the vertual server ID 1, connection #466. The client "220.127.116.11" sent a "rcpt" command and the SMTP server responded with "550 5.7.1 Unable to relay for firstname.lastname@example.org". The full command sent was "rcpt TO:<email@example.com>". This will probably cause the connection to fail.
I've got hundreds of these in my event log. I just need some help figuring out why some mail is going through and some is not.
Thanks in advance for your help.