Blocklist 101

Blocklists (fka “blacklists”) are a method used by security specialists to ensure malicious users aren’t exploiting their systems. In the email world, that means (for the most part) protecting their users and their infrastructure from spam, phishing, malware and other types of attacks. For marketers, that could mean something’s gone wrong with your list or your campaign.

But landing on a blocklist isn’t the end of the world – often, it’s as simple as an email or form submission once the root cause is identified and fixed.

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So, you’ve been blocked…

If you’ve gotten an alert, received an email about a listing, or noticed in your mailing stats that delivery is down, you’ve come to the right place. With the tools available on this page, you’ll be able to get that block removed expeditiously.

As always, feel free to reach out to the Deliverability team if you have any questions or require any assistance.

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What you will need

For nearly all blocklist mitigation processes, clients will need the following information:

1. Contact info for either…

   1. the deliverability lead on the clients' team, or

   2. one of the DLV specialists.

2. The IP or domain name being blocked.

3. The SMTP error code, and anything else that alerted the client or DLV team to the block.

   1. Not sure what you’re looking for? The SMTP Field Manual provides a wealth of background info for most of the bounce messages you’re likely to see. https://smtpfieldmanual.com/

4. A valid reason the mail should not be blocked.

Cloudmark Blocks

Cloudmark is a service provided by Proofpoint to help service providers protect their email networks from abuse and spam.

From their website:

Cloudmark Sender Intelligence™ (CSI) is a comprehensive global sender monitoring and analysis system that delivers timely and accurate reputation on good, bad, and suspect senders. CSI uses real-time data from Cloudmark's Global Threat Network™ system to create the industry's most comprehensive sender reputation service.

If you believe the reputation of your IP address is not correct or if the reputation has changed, you may request a reset of all related email traffic statistics within CSI for your IP address.

Please note this is not a portal for submitting complaints regarding content based spam signatures. Those requests must be directed at the service provider who is blocking the message. This portal will only accept statistical reset requests for IP addresses published by Cloudmark Sender Intelligence.

If you find your mail is being blocked by Cloudmark CSI, the following form is used to submit a mitigation request: https://csi.cloudmark.com/en/reset/

Information needed to submit request:

• Contact Name

• Title

• Company

• Email Address

• Phone Number

• IP address being blocked

• Domain name that the IP represents

• Exact SMTP error string received

• Comment (any additional info, context, etc to ensure reset is successful)

Clients should reach out to the Deliverability team to ensure proper mitigation.

Proofpoint Blocks

Proofpoint is a filtering/anti-abuse application used by email providers to protect against malware, spam and other types of abuse. You're most likely to identify Proofpoint as a source of blocks or delays by reading the bounce messages. SMTP Field Manual maintains a list, but the TL;DR is if it says "Proofpoint" in the message, you're dealing with Proofpoint.

The first step to take is to find out if your sending IP has been listed. You can do so by visiting https://ipcheck.proofpoint.com/

Enter the IP address and click the captcha checkbox.

If your IP is listed, clients should reach out to the Deliverability team for mitigation support.

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