Error when sending email from ZOHO VO

Error when sending email from ZOHO VO

The following error message appears when sending email from VO

Reason:Software caused connection abort: connect. Your mail has been placed in outbox for retrying

The following is the system landscape :

WIN 2003 Server
ZOHO VO
WAMP 5.0 Server (Virtual server based on Apache, mySql and pHp)
MS IIS --> SMTP server and FTP Server.

The smtp server is set up without authentication. However, the send action still results in the error message pasted above.

Any relevant pointers will be greatly appreciated.

Regards,
Prakalp