Email Policies

Please note that the following policies are in addition to those outlined in Caltech's Insitute Policy on Acceptable Use of Electronic Information Resources. The Honor Code also applies to use of your access.caltech account, including email.

Some of these policies define email activities that are unacceptable uses of your access.caltech account. If you violate one or more of those policies, IMSS may disable your account without advance notice and for an indefinite length of time.

The purposes of these policies include:

  • To insure that adequate resources are available to all of our account holders to carry out their academic and professional responsibilities.
  • To prevent situations where other Internet providers restrict Caltech's ability to send email to their systems.
  • To avoid legal problems that could negatively affect Caltech.
  • To prevent problems requiring IMSS to divert staff time away from essential duties.

Mass mailings

Caltech email account holders are allowed to send out email to large numbers of recipients. However, please inform us of your intentions before you send out the messages, as we may be able to suggest alternate ways of sending them that do not use our resources excessively. If we detect a large-scale mailing in progress and have not been adequately informed, we may shut down the mailing.

Please see also the section on "Email size and recipient limits" on this page.

Commercial email

Using a Caltech email account to send unsolicited commercial email is absolutely prohibited and will result in your account being disabled.

For more information on dealing with unsolicited commercial email sent to your account, please see this page.

Email with forged header information

Sending email with forged header information is prohibited. Specifically, sending mail with a forged From line is prohibited.

Email harassment

A Caltech email account may not be used to send harassing email. If another user asks you to stop sending them email, stop! If someone complains to us that you are sending them harassing email, we may be forced to disable your account.

Sending email maliciously

Sending large amounts of email to a spammer or harasser as a method of "punishing" them is both ineffective and unethical, and is not allowed.

Email relaying

To prevent spammers from using our mail server for their purposes, IMSS does not allow a computer not on the Caltech computer network to connect to our mail server and send email to an address that does not end in If you attempt this, your message will bounce with a "relaying denied" error. However, if you have an access.caltech account you can take special provisions to send this kind of email. Please see this page for more information.

Email size and recipient limits

Caltech email has a message size limit of 150 MB and a recipient limit of 500 recipients. Any message that tries to pass through it that is too large, or has too many recpients, will be rejected. This applies both to incoming and outgoing mail. For more information, see the "Message Size Limits" section of this page.

If you need to send mail to more than 500 recipients, please contact IMSS about creating a mailing list.

Retention of IMSS email addresses after leaving Caltech

Employees who do not leave the Institute in good standing immediately lose access to all IMSS computer resources, and mail to their former IMSS email address will not be forwarded.

Employees who officially retire from Caltech (shown by their having a valid Caltech ID card that lists them as a "Retiree") may retain their access.caltech account and associated email address indefinitely. If this applies to you, please contact us at (request type IMSS-->Accounts-->Account Reclassification) and we will make a note of your new status.

People in other situations (employees leaving in good standing, graduated students, etc.) who leave Caltech will have their access.caltech account deleted at some point within a year of their departure. IMSS will forward mail sent to their former address to the location of their choice for a year, or until they request us to stop the forwarding, whichever comes first. There is no option to extend this time limit by paying a fee. If your account is scheduled for deletion, you will receive email that explains how to set up the forwarding.

Aliases and email address changes

IMSS controls the mail servers that provide email service for messages sent to addresses, among others. We will set up email aliases forwarding to access.caltech accounts or other Caltech mail servers by request. We will also set up aliases to non-Caltech mail servers to support our "forwarding for a year" policy (explained above) or to support other Caltech-related activities.

In the case of situations where two people or organizations request the same email address or alias, IMSS will grant it to the first requester, unless the later requester is an organization which we determine has a more legitimate claim to the name.

IMSS' policy is that we will not change account usernames for the purpose of avoiding spam. However, if you are receiving spam sent to your email address and would like to make the @yourdomain address nonfunctional, please submit a request at (request type IMSS-->Email & Calendar-->Other). For more information on dealing with spam sent to your access.caltech account, please see this page.

If you are going to print an email address on business cards or letterheads or otherwise publish it, please make sure that the address is functional before you have those items printed. If you make a mistake, we may not be able to configure our systems to work around it.

Creation of additional accounts for email purposes

IMSS policy is that one person is entitled to one account. We will not create additional email addresses for an individual for the purpose of separating work and personal email, avoiding spam, etc. Please contact the IMSS Help Desk if you want assitance in using your email client to process mail to your single account more effectively.

Note that the IMSS mail server is configured so that mail sent to an address of the form will be delivered to, allowing more effective filtering. Please see this page for more information.

IMSS will create email accounts for organizations, which includes administrative offices that pass from individual to individual, and research groups or laboratories. For more information on accounts not attached to a particular person, please see this page.

Use of your account by others

An access.caltech account is to be used by the individual for whom it was created. It is against our policies to let others use your account to send and receive email, especially if they are not affiliated with Caltech.

Please be careful when using software that allows you to send email (such as a web browser) that you do not leave it set up so that someone else could send email pretending to be you. This is especially important with shared computers or computers in public places.