MessageLabs EMEA PR manager Ilke Kaufmann said the review was at a 'very early stage', adding that MessageLabs would draw up a shortlist 'soon'.
She revealed the review of HBL's brief had been motivated by the international expansion of the company's business.
HBL head of broadcast Hilary Jeffs said the agency had been assured it would be invited to repitch.
HBL won the tech category of last year's PRWeek Awards for a MessageLabs campaign highlighting a rise in the use of bogus financial service company emails to dupe people into giving their personal details.
The campaign highlighted a 216,000 rise in such 'phishing' mails between September 2003 and March 2004, and positioned MessageLabs as an expert in the area of email security management.
MessageLabs' review comes eight months after sister firm Star dropped HBL from a £10,000-a-month B2B brief. Bite Communications replaced HBL (PRWeek, 3 December 2004).
MessageLabs is an independently owned private company with more than 12,000 clients in eight countries. The company competes in the email security market with Symantec and BlackSpider Technologies.
The company is preparing to launch new services to customers in the fields of disaster recovery, message archiving and the filtering of instant messaging and web traffic later this year.