Mass Email Deliverability Frequently Asked Questions


Deliverability Tips

  1. Check out full details on Email Deliverability Best Practices from Salesforce Marketing Cloud documentation.
  2. Surge in list size can trigger a blacklisting or lower your sender reputation: If the size of an email list grows by a lot in a short time, most Internet and email service providers will suspect a list has been purchased.
  3. Bad lead data: Low open rates likely correlate with your email address not being trusted.
  4. Clean up deliverability:
    1. Ensure everyone actively opts in.
    2. Send a re-permissioning campaign to inactive subscribers.
    3. Track records of proof of consent, required by GDPR and other international spam laws.
  5. Dos and don’ts:
    1. Don’t repeatedly send the same or similar content.
    2. Don’t send attachments.
    3. Do watch your sending frequency: send regularly but don’t overwhelm.
    4. Don’t use punctuation like exclamation marks or words often used by spammers.
    5. Don’t BCC your list.
    6. Don’t use too many images. Balance between images and text.
    7. Don’t use all caps. Emphasize using bold, italics, or underlining.
    8. Don't use spam trigger words.
  6. Sunsetting: Remove email addresses from your list if they don’t open or click your emails. It’ll increase sender reputation, open and click rate, and decrease spam reports and unsubscribes.
  7. Types of blacklists:
    1. Public:
      1. Can be directly checked (see below).
    2. Enterprise SPAM Firewalls:
      1. Subset of Public blacklists that are used by corporate IT departments.
      2. Include Microsoft, Barracuda, McAfee, etc.
    3. Private/ISP blacklists
      1. Internal, from services like Gmail, Outlook, Yahoo.
      2. Monitor email tracking reports to see if you’re receiving blocked bounces.
  8. Email message headers can provide additional insights. Specifically, the Bulk Complaint Level (BCL)Spam Confidence Level (SCL), and the Phishing Confidence Level (PCL) assigned to your message contribute to the (un)likelihood of your message getting to the Inbox.

Use Litmus and Content Detective

The university has purchased a limited number of Litmus Enterprise licenses for departments engaged in high volumes of mass email marketing. Litmus provides you with previews of your email in 70+ email clients including desktop and mobile devices, helping you to catch rendering issues before your message goes out. Litmus can also perform message delivery analytics and inform you of inbox placement for various email services like Gmail, Yahoo!, AOL, and more.

The Marketing Cloud Content Detective scans your Marketing Cloud email for trigger words and alerts you to any issues with your email content. Check out the Marketing Cloud documentation and make sure to run it every time!

How to prevent a message from ending up in the Junk folder?

Check your email's "Spam Score" to make sure it can pass through to the Inbox.

The "spam confidence level" is a score between -1 and 9 that is assigned to your message based on several factors. Email services like Microsoft don't disclose the full details of their scoring algorithm in order to keep the spammers guessing (and us, too), but there are a few things that we know. For example:

  • If a single message goes to multiple recipients, the score may go up a little.
  • When you send a message but only BCC your recipient list, leaving the To: line blank, the score goes up.
  • If there are many hyperlinks, a large graphic-to-text ratio, dollar signs or several spammy keywords like "Free" "Viagra" "Refinance" "mortgage" or "Work from home" the algorithm will likely raise your spam score.
  • See the list of spam trigger words.

A score of -1 is typically a small, internal email from me to you, for example. Messages with a high score of 7, 8, or 9 typically come from email services on known blacklists, include lots of spammy words, or are trying to hide their true identity by spoofing an email address.

According to Microsoft, our default Office365 threshold for messages at St. Thomas is a 7. So, if you run your message header through the Message Analyzer and you receive a score of 7 or greater, you can count on your message getting filtered to the junk folder.

Check your spam score by pasting your email header in either of the following links:


How to prevent email server, IP address, or domain from appearing on a blacklist?

You can check your email domain against a list of blacklists by checking one of these sites:



Article ID: 97406
Wed 2/5/20 12:33 PM
Fri 10/14/22 12:31 PM

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