Security appliance developer eSoft has updated its email gateway with the ability for users to spam-file or whitelist emails from any device, including a BlackBerry or smartphone. Previously, only Outlook users could train the gateway's Bayesian spam-filter.

It has also added content filtering for data leakage prevention, and a database that automatically identifies incoming mail that's part of a conversation. That should mean you no longer have the annoying experience of waiting for a reply, only to find it stuck in the spam filter, the company claimed.

The updates are included in eSoft's new Email ThreatPak, which runs on its ThreatWall appliances and InstaGate firewalls, said Patrick Walsh, the company's product management and marketing director.

The departmental or company edge is still the best place to do email security, Walsh argued. "There are cloud-based filters, but most companies run their own mailservers, so doing it in the cloud is more complicated," he said.

As well as filtering inbound traffic, eSafe's email gateway also watches outbound email to look for bots - Trojan-infected PCs acting as email relays - on the local network.

"The biggest thing in spam now is bots, they're stealthier and harder to remove, and they mean the cost of sending spam is even lower," said Walsh, who formerly headed eSoft's threat prevention team. "Bot detection still uses deep packet inspection, but it looks for specific behaviour patterns rather than signatures or strings."

He added that eSoft has also tried to make its data leakage features easier to set up and use. "Today, data leakage prevention is mainly used in a content-filtering context, preventing confidential data from leaving the network and quarantining suspect messages," he explained. "We now have a list of check-boxes - what kind of things to look for - to help set up the filtering."

Other new features include the ability to automatically add email footers, plus support for custom SSL certificates and opportunistic encryption. Encryption is enough of a standard among mailservers now that it would be silly not to use it, Walsh said.