[exim] no Mails being sent outside

Hello all,

I use Dovecot and exim4 on a private debian 4 System in our office.
Twice a day I sent email to my normal account with a system summary.

After the last update it doesn't work anymore.
The local Mail within the office works fine.

in /var/log/exim4/mainlog it always says:

        2008-04-19 12:07:34 1JijL2-0000zn-Co == markus@???
        R=smarthost T=remote_smtp_smarthost defer (0): bad base 64
        string in challenge:  CRAM-MD5

what is wrong?

thank you


Markus