As of version 3.3.4, the mail system in Bugzilla doesn't work with SSL/TLS-based SMTP mail servers. The following procedure helps you set up a working Bugzilla configuration that can use an SSL/TLS-based mail server, such as Gmail.

Because Bugzilla can't talk to Gmail directly, you need to install a mail server. One such open source mail server is named "James." I tested it with the version 3.0 nightly build.

1. Download James and extract the zip file.
2. By default, the James server prevents relaying of messages that originate from any non-local clients. To enable relaying, search for the string <mailet match="RemoteAddrNotInNetwork=127.0.0.1/8" in the file <JAMES_HOME>/apps/james/SAR-INF/config.xml and change it to <mailet match="RemoteAddrNotInNetwork=192.168.0.*,127.0.0.1/8", where 192.168.0.* represents your local LAN's IP prefix. (If you are planning to install Bugzilla and James on the same machine, you can skip this step.)
3. Execute <JAMES_HOME>/bin/run.sh (in a Linux environment) or <JAMES_HOME>/bin/run.bat (in Windows).
4. Now log in to Bugzilla as an admin user and select mail_delivery_system from the main screen.
5. On the next page, set the mail_delivery_method to SMTP.
6. Set smtpserver to the IP of the server on which you installed James.
7. Save your changes

You can now test Bugzilla. Because the James mail server is totally Java based, you can use this method for both Linux and Windows systems.