[Mimedefang] Huge messages causing "try again later"

[sysadmin at omsoft.com]

I have been getting messages like this in my syslog:

>Feb 24 14:06:10 hostname sm-mta[1512]: [ID 801593 mail.info] i1OM3HKq001512:
>	to=<user at domain>, delay=00:02:53, pri=20758560, stat=Please try again later

It appears to only be on messages that are 10MB or larger. Is sendmail timing 
out waiting for a response from a mimdefang child perhaps? Is there a way I 
could prevent mimedefang from examining messages this large?

Thanks,

Lucas