Email system users at FastMail are provided with virus checks of all incoming messages and file attachments. When harmful code of any type is found (viruses, internet-worms, Trojan horses etc.) you will receive a warning. FastMail's anti-virus reliably fends off most virus attacks. It is able to scan a wide range of archives and compressed files and supports any amount of file attachment levels.
If you receive a virus while scanning is enabled (in preferences), the mail is discarded, and you will receive a notification that a message to you was discarded, and you will also be told who sent it.
However there is no guarantee that a virus is present; sometimes safe files are marked incorrectly, and sometimes unsafe files are not identified. For this reason we recommend that you take precautions with files received via email - especially messages sent from unfamiliar sources.
When the virus-scanner detects a virus in an email sent to you it will discard the email that contains the virus and send you a notification to let you know who sent you which virus. However, since most viruses send out mails with forged addresses, this information is oftentimes not very useful. By turning this option on you will no longer receive notifications of mails being stopped by the virus-scanner.