User password with special characters reset themselves?

[easytouch]

I have one user where his pasword stops working suddenly.

He uses special characters in his password:

<ABC§xyz>08

I have the feeling that the brackets mess something up with LDAP?
Some cronjob must be running where his password becomes unusable?

Which special characters are allowed?

Zimbra Version:

4.5.6_GA_1044.DEBIAN3.1
Vlient Release: 20070706142305
Build Date: 20070706-1425