Email Blacklisting Prevention Best Practices


Blacklisting is a common problem that affects other universities and organizations. On occasion, messages sent from a University of Pittsburgh email account can be delayed or rejected because a University email server has been placed on a "blacklist". A blacklist is a list of mail servers that send large amounts of unsolicited bulk email (or "spam"). Some email service providers delay or block the delivery of messages sent from servers that appear on a blacklist.

Forwarding University email to non-University email accounts without spam filtering enabled is the most significant cause of blacklisting at the University. Some University email users choose to forward their email messages to outside email accounts like Gmail or Yahoo. In these cases, spam messages are also forwarded to those outside email accounts. Email services like Google then mistakenly identify the University's servers as the origin of the spam attacks and refuse or delay the delivery of email from the University.

Spam filtering is automatically enabled for all University email accounts. This helps prevent spam messages from being forwarded to outside email accounts and helps prevent the University from being placed on email blacklists.

This page explains more about why blacklisting occurs and what you can do to help prevent the University from being blacklisted.



What is an email blacklist?

A number of anti-spam services exist that publish blacklists containing the names of email servers that are used to send spam. Administrators of email systems can configure their email servers to delay or block the delivery of any email message that comes from a server that appears on a blacklist. By doing so, the system administrators hope to reduce the amount of spam received by their systems.

Why would the University of Pittsburgh's email servers be placed on an email blacklist?

The University permits students, faculty, and staff to forward email messages to outside (non-University) email accounts (such as personal accounts on Gmail, Yahoo!, or Hotmail). University addresses that forward mail to non-University email accounts also forward spam to those non-University accounts if spam filtering is not enabled. Because the email message was forwarded from the University, Google or Yahoo assume that the University's email server is being used to send out spam. As a result, the University's email server is placed on their blacklist.

Why does blacklisting cause my email to bounce back to me?

If you send a message from your University email account to someone whose email system uses blacklists to block mail, your email will be returned without being delivered. This will only occur if the University email servers are being blacklisted at the time that you send your email. Blacklist entries can expire after several hours, so you may not notice an issue. However, the University's email servers can sometimes be placed on a blacklist for longer periods of time.

What can the University of Pittsburgh do about this?

Pitt Information Technology continues to actively investigate all available technical solutions that may help to prevent the University from being blacklisted. As of September 7, 2008, spam filtering was automatically enabled for all University students, faculty, and staff who forward their University email to outside accounts. This helps to prevent spam from being forwarded to non-University accounts and helps to prevent the University from being placed on blacklists.

Having the University removed from a blacklist can be problematic. Most anti-spam services are automated and have no actual representative to whom questions and complaints can be addressed. In most cases, they provide only an online form that needs to be completed. Such forms may temporarily remove the University from a blacklist. However, the University is placed back on the blacklist as soon as the anti-spam service receives new reports of forwarded spam being sent from University email servers. Most blacklisting services are not sophisticated enough to understand that the University's email servers are forwarding email messages as intended and are not the actual source of spam messages.

What can I do to help prevent blacklisting?

Pitt IT strongly recommends that you do not forward your University email to non-University addresses. Your University email address ( is used by the University for all official electronic mail. If you choose to read your email from another address, you remain responsible for all messages that are sent to your University email address.

What can I do if an email message I send is not delivered because of blacklisting?

It's usually best to contact the person to whom you were trying to send the email message. Explain to them that your legitimate email was rejected by their system, and ask them to report the problem to their Help Desk.

Whom do I contact if I have additional questions?

If you have questions or would like additional information, please contact the Technology Help Desk at 412-624-HELP (4357).


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Tue 7/18/23 2:24 PM
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