E-mails not sent via Gmail smtp

Hi,

I am using CB 1.8 (and 1.7.1 before with the same problem). Joomla 1.5.25.

I have set my mailing system to SMTP
port: 465
SMTP Host: smtp.gmail.com

All system e-mails works well except the CB messages.

When I resend a confirmation e-mail to one person the CB says sent confirmation emails to 1 users but nothing in the mailbox nor in the sent messages of the gmail account.

It is just like CB was not using the smtp server.

I must have done a misconfiguration somewhere.

Does somebody have suggestions for me?

I am lost and I need to go live next week.

All the other messages are sent normally only CB ones are not sent.