MailMarshal is installed as an email gateway and may be used in conjunction with any SMTP-compatible email server. However, MailMarshal SMTP also supports POP3 mail protocols, and can act as a POP3 mail server for up to 300 users. It can also collect emails via POP3 for situations where there is a dial-up connection to the Internet.
The MailMarshal software must be installed on a PC running Windows 2000, XP Professional, or Windows 2003 Server. Where an existing email server is running on one of these operating systems, MailMarshal can run on the same machine. Even in this scenario, MailMarshal SMTP cannot police internal emails within a single email server, although there is another product, called MailMarshal for Exchange, which fulfils that role in a Microsoft Exchange environment.
Anti-spam functionality starts with host blocking, which can be based on any number of third-party public Real-time Blackhole Lists (RBLs). The next component, called SpamCensor, is continually updated by downloads from NetIQ and uses a weighted combination of factors derived from message analysis to determine how likely a message is to be spam.
Another component, called TextCensor, is highly configurable using a scripting language to scan for keywords and phrases in quite complicated ways. This can be used to protect against confidential information being emailed to the wrong people etc. TextCensor policies can be different for each user based on username, department, domain, etc.
Action taken can involve blocking and quarantining a message, rejecting it (thus conserving bandwidth), or copying it to the system administrator while allowing it through. Attachments may be blocked by file type, and MailMarshal can look inside archive files such as ZIP files. It can also block encrypted messages that cannot be decrypted by MailMarshal for content examination.
Outgoing messages above a user-configurable size may be blocked or parked, which means that they are delayed and transmitted outside normal working hours, for example, to conserve bandwidth. This size limit may also be applied to bulk mailings where each individual message is small but, because of the number of recipients, a large amount of bandwidth would be consumed.
Anti-virus functionality is provided by integrating with other vendors' anti-virus products, and supports virtually all third-party scanners.
Optionally there is support for PKI-based S/MIME encryption and decryption, together with digital signatures generated at the gateway.