How to turn off auto-subscribe requests of jabber?

Hi,

I am using asterisk and configured jabber.conf to log in into my
GoogleTalk account.
Unfortunately, Asterisk sends subscription requests on every
startup.

Some of my Google contacts do not use Jabber at all, however
they have google/gmx/web.de accounts (which offer jabber).
Those contacts get an e-mail on every restart of Asterisk, because
asterisk wants to subscribe to the online status of those contacts:

“Greetings! I am the Asterisk Open Source PBX and I want to subscribe to your presence”

How can I turn off the “subscribe to all contacts” feature in jabber.conf?
autoregister=no
does not disable it.

Thank You in advance,
Johann Uhrmann