Hi,
I'm Junaid Subhani's team member. Let me further clarify our email architecture for our system email alerts.
All unix/linux machines sendmail client is set to use two MTA relay sendmail servers internally in our network.
Then those two MTA relay sendmail servers forwards all the email to our company's microsoft exchange server (Microsoft servers are managed and administered by a seperate windows team).
Then mircosoft exchange server delivers the system alerts to valid microsoft exchange email IDs, e.g.
xyz@waridtel.com.
So basically submit.cf of all the client machines has the IP address of internal network MTA relay sendmail server and MTA sendmail relay server has the IP of Microsoft exchange server for D{MTAHost} in submit.cf.
All the system email alerts configured by us and different application/database team (in their scripts) is properly being delivered.
Now the problem we are facing is this. Along with all the system alerts emails, all of the sendmail client machines are also sending out native OS users system generated emails (to the native user ) as well. And ...... our internal network MTA relay sendmail server obviously also relay them to our domain's microsoft exchange server, which obviously cannot recognize the destination address (e.g.
user@server-hostname.waridtel.com) floods our outbound email gateway (sendmail server) with all those unwanted emails and overwhelms the mail queue.
So far, we concluded to use '.forward' option to at least deliver all the emails to proper email address (xyz@waridtel.com) of the respective owner team of the unix/linux system user. That way our corporate outbound sendmail email gateway will not be brought down due to 100,000+ unwanted system users email everyday.
Another option we have read somewhere is to configure /etc/mail/access file on the internal MTA relay sendmail server, which would discard or reject any email addressed to
user@server-hostname.warditel.com. But we are not sure about the syntax to be used. Whether we can use wild card options to reject/discard all emails addressed to
user@server-hostname.waridtel.com or we have to add lines for each and every user of all the servers.