Amavis virus detection

Hi, I've just installed SuSE 8.1 with Postfix and Amavis and have tried sending the eicar.com virus pattern in an attachment. This worked great - the virus was detected and blocked. However, I also tried sending a copy of Bugbear to one of my own users externally via a web-based email service, (onetel - similar to hotmail, et al), and this was sent through to the user without being blocked :( The message headers contains the entry X-Virus-Scanned: by AMaViS 0.3.12pre8 Any ideas, anyone? Rgds Andy