[BlueOnyx:10446] User Quota warning - why?

[Dirk Estenfeld]

Hello,

on a 5106R System I have a User with the following quota

Disk quotas for user grah (uid 586):
     Filesystem  blocks   quota   limit   grace   files   quota   limit   grace
/dev/mapper/VolGroup00-home
                1045892  2048000 2049024              37       0       0

2 GB quota; 1 GB in use.

But this user is getting the following message:

>Sie belegen momentan mehr Festplattenspeicher, als Ihnen zugestanden 
>wurde. Entfernen Sie nicht mehr benötigte E-Mails und Dateien, um das 
>Problem zu beheben.
(it means user near/over quota)

Only this user is getting this message - strange.
But in maillog I can see that root is sending the message directly to the user. It is no forward or list which is getting the warning.

How can I find out why this email is generated and which program is generating the near/over quota emails?

Regards,
Dirk