Alvin: I am actually using their class 2 certificate so I did this: cat mail.nsa-lp.com.crt sub.class2.server.ca.cer ca.cer > mail.nsa-lp.com.all.crt
Then, I changed my main.cf file to reference it: # Enable SMTP TLS smtpd_tls_cert_file = /etc/ssl/mail.nsa-lp.com.all.crt smtpd_tls_key_file = /etc/ssl/mail.nsa-lp.com.key smtpd_tls_security_level = may smtpd_tls_auth_only = yes Outlook is still not able to send a test message through my server. When I try to connect using: openssl s_client -connect mail.nsa-lp.com:25 -starttls smtp I still get a complaint about a self signed certificate. If I try to send a message using the manual commands, I still get Error: no valid recipients Like I said in my earlier message to Patrick, Outlook does not complain about the certificate when I use pop3s to get a message. I am not sure what to do now. Any ideas? Thanks, Neil -- Neil Aggarwal, (972)834-1565, http://UnmeteredVPS.net/centos Virtual private server with CentOS 6 preinstalled Unmetered bandwidth = no overage charges -----Original Message----- Try copying the contents of the chain certificates `sub.class1.server.ca.pem` then `ca.pem` to the contents of your public certificate, from depth to root.