Hello.

Please help me to fix the below issue.
Setup: Zimbra server is configured to use POP3(995), IMAP(993) and smtp(465 with SSL/TLS and port 25).
zimbra version: 6.0.6.Mail communication is working fine through the above mentioned ports when i am using zimbra desktop client/ MS-Oulook/ Thunderbird and outlook express.I am trying to send a notification email via internet through an application running on Windows server 2008R2 using .netframework3.5. Mail server and application server can communicate only through internet.In my code i enter mail server name and give port number.
Sender mail id is a domain present on the mail server which i am using as smtp.In below e.g. domain xyz.com is present on the mail server.
Following are the test cases and there respective outcomes:
1.Port no:25 SSL setting:False
sender domain: abc@xyz.com recpient domain:mng@xyz.com.
result: mail gets delivered

2.Port no:25 SSL setting:False
sender domain: abc@xyz.com recpient domain: abc@gmail.com or abc@yahoo.com
result: mail delivery fails with error relay access denied.
logs in zimbra.log file: 554 5.7.1 <abc@gmail.com>: Relay access denied; from=<abc@xyz.com> to=<abc@gmail.com> proto=ESMTP