Linux.com reported that Trend Micros has been working to extract a patent license from Barracude Networks for a number of years and more recently brought the complaint to the International Trade Commission since the key software in question is written in international locations as part of the [[ClamAV]] open source project.
A couple of key facts to consider:
Trend Micro has a patent issued in 1997 on the use of SMTP and FTP services in a proxy device for anti-virus.
The patent has been licensed by Symantec, McAfee and Fortinet.
Barracuda's implementation, in an interesting twist involves [[Free and Open Source Software]] (FOSS) which is not a party to the lawsuit although it is the critical technology allegedly infringing on the patent.
The ClamAV initiative, although probably infringing on the patent (I'm not an attorney or a patent specialist) would be useless since there is no money to be had doing so. Remove the money, and there's no benefit to suing the ClamAV people directly. Besides, who do you sue? All the software developers working on the project? Just the hosting sites? Yuck, this is draconian.
The reason Trend Micro sued Barracuda is because Barracuda has money. They are making real money from the Intellectual Property in question, and so if ordered to by the power of the state can be forced to pay a licensing fee to Trend Micro.
They engaged the suit with the ITC because the ITC is thought to be more inventor friendly and can make decisions faster.