Java Mail mystery - SMTP blocked?

Question

I have a Java program which uses javax.mail to send an SMTP message. This program works fine on a Linux box, I want to emphasize that beforehand. When I try this same cod

Answer 1

Synantec EP 12.1 RU5 fixes your issue.

Symantec Endpoint Protection blocks email sent by Java mail client

Fix ID: 3399185

Symptom: The Internet Email Auto-Protect feature of Symantec Endpoint Protection blocks SMTP email sent by a Java mail client.

Solution: Updated the Internet Email Auto-Protect driver to allow processing of IPv4-mapped IPv6 addresses.