Very long filenames?

[Ken Goods]

I received this notification this morning. 

Subject: Re: 
MessageID: l5TDre77020228
Quarantine: /var/spool/MailScanner/quarantine/20070629/l5TDre77020228
Report: MailScanner: Very long filenames are good signs of attacks against
Microsoft e-mail packages (TCA2AR759CAY3E.jpg)

I was just wondering how long is a *long* filename? This doesn't appear to
be excessive as we commonly get Word documents that are much longer. I
looked around but couldn't find the upper limit that triggers this rule.

Thanks,
Ken

Ken Goods
Network Administrator
CropUSA Insurance, Inc.