Help! Queue file getting VERY large

[Guenthner, Ralf DIRZ 612]

Hi

I've been using qmail for a year now with no problems. But now the HD of
the Linux system is filling up and by means of find I found a 91 MB (!)
file in the directory /var/qmail/queue/mess/46458. 

What the hell is this file and how can I decrease its size? It seems to
contain parts of all messages ever sent??

Any advice via e-mail or in the list would be appreciated, before this
file eats up my whole disk <g>

Regards
Ralf