Postini is a service that Google provides for all Connecticut College faculty and staff email accounts. It is not available for student accounts. It's main benefit for staff and faculty is that it provides an extra level of spam filtering on your email account.
You can log in to your Postini account by opening this page https://login.postini.com/ and then clicking on the "Postini Login" link on the right side of that page. If the password that you entered is incorrect there will be a link that you can use to have Postini send you a new temporary password for your account.
All incoming email addressed to faculty and staff email accounts are passed through Postini's spam filters first before being delivered to your Google account. Any emails suspected of being spam or containing a virus attachment are quarantined.
Once a day, usually around 9 p.m., Postini sends an email to you listing all of the messages that were quarantined that day. There is a link in those emails that will take you to your Postini "Message Center" where you can browse all quarantined messages from the past 30 days as well as adjust the sensitivity settings of the spam filters and add email addresses to your whitelist so that messages from those addresses are never quarantined. Quarantined messages are deleted after 30 days.
If an email that you are expecting hasn't arrived and it's not in your Google Mail spam folder, then you should remember to check your Postini quarantine rather than waiting for the quarantine email to arrive that night.
Note: If you try to add too many addresses to your whitelist, you will get a "value too long" error message. This will happen when you exceed the 4000-character limit for all of your whitelisted addresses. The only solution is to review your approved senders list and look for any duplicates and delete them to free up some space. This page explains how you can find the total number of characters your approved senders list is currently using viewing the full headers on a message that has been processed by Postini. To do this you need to look at an email that was quarantined which you then clicked on the Deliver button to have it delivered to your Inbox. Then open that message in Google Mail and click on the down triangle next to the "Reply" button and choose "Show Original". Towards the end of all the header information you should find the "X-pstn-addresses:" header at the end of which you will see two numbers in brackets - the first is the total number of characters that your approved senders list is using, the second number is the number of addresses in your approved sender list.