The news software also has better compliance features, enabling users to tie the system into existing archiving products, according to SonicWall’s senior director of product management Gleb Budman.
Directory harvest attacks are one type of connection-level spamming, where spammers send thousands of SMTP messages to an email server in an attempt to determine through trial and error what email addresses are active on a given domain.
SonicWall said it could handle DHAs in previous versions, by integrating with the user directory. The 5.0 version can also prevent these and other types of attacks by throttling sessions from IP addresses that make excessive requests, the firm said.
On the compliance front, which comes as an add-on subscription, the company has added the ability to archive emails on-box or to a third-party archive store, when their contents meet admin-defined criteria.
Encryption support has also been increased. While the old version supported TLS for session-level encryption, the new version can link up with encryption servers such as PGP to encrypt whole messages when they meet the criteria, SonicWall said.
