What is a "Fingerprint" and How Can It Affect Email Delivery?
Posted by on 10 June 2014 10:16 AM
What is a "Fingerprint" and How Can It Affect Email Delivery?

What is a "Fingerprint" and How Can It Affect Email Delivery?



On occasion, inbound mail may be denied with a 554 denied error.

Typically this will happen when the sender's domain and/or IP address has been "fingerprinted" - typically for at least one of the reasons below:

1. The sender has sent a recent email blast that contained a number of invalid recipients

2. The sender has sent a recent message that was received by a "honeypot".  In short, a honeypot is a server with

    fictitious email addresses whose sole purpose is to sit and wait for email to be sent to it. 
    Any message received is automatically classified as spam because it is
truly unsolicited

3. The sender has sent email to a recipient (not necessarily a McAfee SaaS Email Protection customer) who then     reported 
the email to their ISP as potential spam. This may happen especially if the sender is not using or

    honoring opt-out links in their messages.

A "fingerprint" is a hash typically placed upon a static piece of any e-mail - typically a portion of a signature block.  As noted above, it is typically the sender's outbound habits that cause the fingerprint to be put in place, however, it is possible that in some cases the problem has been caused by the recipient due to their own sending practices.  The sign that this is the case is if a McAfee SaaS Email Protection customer has inbound replies or forwards back to their domain being denied or quarantined as suspected spam.

In the event of a sender being the cause of the 554 denied error, there are three ways of addressing the problem:

1 - Add the sender's domain to your domain-level sender allow list in the Email Protection service

2 - Ask the sender to remove their signature from the e-mail

3 - Log a service request with your Email Protection support provider and request that the scoring be challenged.  In this case, the McAfee Threat Management team will address the challenge and, in many cases, be able to clear the fingerprint to allow messages to be delivered.  NOTE - removal/clearing of a fingerprint is not guaranteed.

ERROR: This domain name does not match domain registered in the license key file (, allowed domains:,localhost, please change the product path to match the domain under Admin CP > Settings > General Settings
This product will not work properly unless untill that value is changed.

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