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School of Pharmacy

UCSF School of Pharmacy

How e-mail reaches you (or not)

To better understand how to deal with spam, it's helpful to understand the path an e-mail message takes to reach you at your UCSF e-mail account. This enables you to understand how spam can be deleted as well as what might be happening to legitimate messages that seem to disappear.

1.

A message is created and sent to your e-mail address.

If this message is spam, it might originate with a human spammer running a script or other program which automates the process for him or her, or it might be a zombie computer -- a computer that has been compromised by a hacker and used to send spam, usually without the knowledge of that computer's owner.

2.

A computer at UCSF reviews and acts upon the message in order to weed out spam.

We call this computer our spam firewall, which receives its name based on the concepts of network firewalls and construction firewalls. The spam firewall filtering takes place before the message reaches your e-mail application.

First, we check whitelists and blacklists...

If the message is from a sender on your whitelist

it is delivered to your e-mail application (go to step #3 below). You can specify that messages from certain e-mail addresses or e-mail domains will always be delivered to you by adding them to your whitelist, which you can edit in Spam Firewall preferences.

If the message is from a sender on your blacklist

it is deleted. You can block e-mail addresses or e-mail domains by adding them to your blacklist, which you can edit in Spam Firewall preferences.

If neither whitelist nor blacklist,

the message is assigned a spam score. The spam firewall makes a calculated guess as to how similar the message is to previous messages known to be spam. A spam score value between 0 and 10 is assigned to the message: 0 = least likely to be spam, 10 = most likely to be spam. You can control what happens to these messages in Spam Firewall preferences. (Go to the next line below.)

Next, one of two things happens to the message based on its spam score:

The message is quarantined

if it has a spam score higher than your Quarantine setting but lower than your Block setting. These messages are held for 30 days and are available for you to retrieve by examining your quarantine list in Spam Firewall. These messages never reach your inbox unless you explicitly request their delivery.

The message is blocked

if it has a spam score higher than your Block setting. These blocked messages are deleted at the server, and you will never see them, even in your Quarantine. The default Block setting is 7. Messages scoring above 7 are most likely to be spam.

The message is delivered

to your email application if it has a spam score lower than your Quarantine setting.

For more details on adjusting server-side spam filtering settings, see Spam Firewall. The tagging feature has been intentionally disabled. It was requested to be turned off by the CIO because the community didn't like to have email tagged.

3.

Your e-mail application reviews and acts upon the message in order to weed out spam.

Messages may be delivered to your inbox, deleted, or quarantined based on spam filtering settings in your e-mail application. The details of this filtering differ based on the e-mail application you use. Consult the online help or vendor of the e-mail application for help with its spam filtering features.

If a message is not quarantined or deleted by your e-mail application, it is delivered to your inbox.

4.

A message appears in your inbox.

Messages that reach your inbox have had an arduous journey, having gotten past both the UCSF Spam Firewall and your e-mail application's spam filtering.

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