Caltech Mail Protection Gateway

Since its implementation in May 2017, the Mail Protection Gateway (MPG) has blocked and filtered 90% of all incoming Caltech email, including:

  • 389,500,000 emails from questionable senders
  • 13,000,000 spam emails
  • 4,778 virus emails
  • 364,900 emails with malicious links

The MPG service, provided by Cisco Email Security, helps protect against advanced email threats and reduce unsolicited email (spam).

The MPG quarantines suspected spam for up to 45 days. During that time, you can log in to retrieve legitimate email from the Spam Quarantine, add senders to a personal safelist, or take no action if the email is actual spam.


Can I check the Spam Quarantine at any time? 

To check the quarantine at any time, visit

Is my email completely protected now?

No, unfortunately email is never fully secure. You should still be cautious when receiving email (especially attachments) that you were not expecting.

How do I know if I have email in my Spam Quarantine?

Spam quarantine notification summaries are sent weekly and will appear in your inbox from Caltech IMSS <>. An example is shown below:

Why is it that when I go to the Spam Quarantine (, I get redirected to a non-Caltech site (

The Mail Protection Gateway is a cloud based service provided by Cisco. The qurantined email resides on Cisco servers and we cannot customize their URL. We created to provide a URL that is easier to remember. 

How can I stop receiving the weekly Spam Quarantine summary?

If you would like to opt out from receiving the weekly summary of your quarantine messages, please submit a ticket via (request type: IMSS > Email & Calendar > Mail Protection Gateway).

How can I get email(s) out of the Quarantine and into my Inbox?

To release a message from the quarantine to your inbox, click on the link in your email notification to view your email quarantine. Select the message(s) to release and choose the Action "Release". Click submit to complete the process.

If a quarantined message is spam, you have the option of using the "Delete" action. However, if you choose to do nothing, the message will automatically be removed after 45 days.

A legitimate email is in my quarantine. How do I make sure that this sender's emails get delivered to my Inbox?

You may choose to release a message from the quarantine to your inbox, and add the sender to a personal safelist to ensure that future messages are delivered directly to your inbox.  To do this, select your message(s) and the Action "Release and Add to Safelist".

Removing Message Tagging from the Subject Line

You can create email rules to filter on specific tags. Please check the Message Tagging page, for instructions on how to do this.

If you would like to remove ALL these tags from your Subject lines, please submit a ticket via (request type: IMSS > Email & Calendar > Mail Protection Gateway).


Please note, that we will NOT be able to remove protection tags such as:

[Possible Phish Message]
[Possible Malware Message]

Who can I contact with questions or concerns? 

For any questions or concerns, please contact the Help Desk at (Request Type: IMSS > Email & Calendar > Mail Protection Gateway) or x3500.