IT at UNSW - Mail Gateway - Spam and Viruses

Email borne spam and viruses are an ever increasing problem. The IT at UNSW central mail delivery system (smtp.unsw.edu.au) provides a reliable and accurate method of significantly reducing this problem. The system is made up of a number of servers in a load balanced, geographically redundant server farm.

Measures used to reduce email spam and viruses include:

Reject Partial or Fragmented Emails

The gateway will reject partial or fragmented email. This is because the distributed nature of the anti-virus system cannot piece together a full email for virus scanning, and in practice few if any non-spam mail messages are fragmented.

Reject Oversized Emails

The gateway will reject messages over 20 MB - either in total, or when attachments are uncompressed (e.g. zip format). To send files larger than 20 MB, it is recommended using another service such as http://www.yousendit.com/.

Virus Scanning

Mail is passed from the gateways on to the anti-virus/spam tagging scanners.

Virus pattern signatures are checked for updates every 30 minutes.
Mass mail viruses identified by Trend IMSS, such as Melissa and Sobig, are silently deleted.
Ordinary mails that contain a virus are "cleaned" of the virus and sent on to the destination.

Spam Tagging

The spam tagging software is IronPort which tags mail it identifies as spam. It is up to your departmental mail server or own mail client to decide what to do with those tags. (e.g. file mail tagged as spam into a "Junk Mail" folder)

IronPort uses a wide variety of local and network tests (info 1 & info 2) to identify spam signatures.
Mail is then tagged with a label in the mail header identifying the level of confidence IronPort has that the email is actually spam.
This spam tagging will only have an affect if your departmental mail server and/or mail client acts on these tags.
If you have a mail client capable of filtering, it should act on the mail headers added by IronPort. The headers will look something like:
```
X-Spam-Flag: YES
X-Spam-Level: *******
```
Mail that is considered to be free of SPAM will have no tags added.

Mail that is considered to be possible SPAM has these tags added:

X-Spam-Score: 3
X-Spam-Flag: YES
X-Spam-Level: ***
X-Spam-Status: Yes, score=3.0 required=5

Mail that is considered to be definitely SPAM has these tags added:

X-Spam-Score: 5
X-Spam-Flag: YES
X-Spam-Level: *****
X-Spam-Status: Yes, score=5.0 required=5

Are You Protected?

All email sent to user@unsw.edu.au goes through the central mail system. Also, all departmental email that is routed through the central mail system is protected. Your mail administrator will be able to advise if your department uses the central mail system.