No financial details have been disclosed, but the acquisition is aimed at bolstering Marshal8e6's ability to detect blended e-mail and web threats.
Blended threats make up 42% of spam and this is likely to increase and mature in the next year, said Bradley Anstis, director of technical strategy at Marshal8e6.
"This type of spam is getting increasingly difficult to detect and we aim to head off this evolving threat with Avinti technology," he said.
According to Anstis, most organisations have well-protected e-mail gateways but less effective defences around web gateways, which is where the threat has moved.
Marshal8e6 plans to release the first Avinti-integrated products in August that will analyse the behaviour of all links within e-mails in a virtual environment.
"E-mail containing links that behave suspiciously within a test virtual environment will be blocked to prevent web-based infections," Anstis said.
The behaviour-based approach does not rely on malware signatures and can therefore provide protection against unknown threats and malware variants.
This acquisition follows the November 2008 merger of UK-based email and web security company Marshal and US-based 8e6 Technologies, a provider of URL filtering technology.