MailScanner, delivers mail sometimes with out scanning

[normat]

Hi every one,

I have a problem with my MailScanner (version 4.30.3).
Normally every thing works fine. Sendmail receive the mails and puts them into /var/spool/mqueue.in.
The MailScanner takes the mails, scans them and puts them into /var/spool/mqueue, from where they get delivered to there destination.

But if I send 4 or more mails with a virus in really short time to the Mailer, the MailScanner delivers them without scanning.

Has someone expired with the same problem???