Subject Line Best Practices
Updated March 30, 2011
Experian CheetahMail
29 Broadway, 6th Floor, New York, NY 10006 • T 212 809 0825 • F 212 809 6378 • www.cheetahmail.com 1
Overview:
While the market place tends to see dropping open rates and less filtering based on content within a
message, CheetahMail recommends that marketers follow industry best practices with the creation of
subject lines.
Best Practices:
Incorporate frequent subject line testing into your email marketing strategy to evaluate the
language that draws the highest response from your subscriber base
Be mindful of common words and phrases that are more likely to be caught in spam filters
Run all content via the CheetahMail Content Evaluator
Creating Subject Lines:
The goal of any subject line is to prompt a subscriber to open your email. Subject lines can convey
information or an emotion to elicit this response. CheetahMail recommends that marketers think about the
following principals in creating subject lines:
• CAN-SPAM Rules: The CAN SPAM Act, the country’s first Federal Spam bill, was officially
signed by George W. Bush on Tuesday, December 16, 2003. To be compliant with the CAN
SPAM Act, marketers are prohibited against using false or deceptive subject lines
• Information: Never underestimate the power of simplicity. The direct approach of a simple
subject line that clearly indicates the information within the marketing message can perform quite
well. For example:
o “20% off Summer Clothes Sale”
o “Announcing our New Spring Line”
o “Invitation to Our Next Webinar”
• Length: Less if often more! Some email clients, such as AOL, by default only display the first 16-
32 characters of a subject line.
Experian CheetahMail
29 Broadway, 6th Floor, New York, NY 10006 • T 212 809 0825 • F 212 809 6378 • www.cheetahmail.com 2
• Branding: Your brand is one of your most valuable assets. Use it wisely and appropriately. If
your “from name” and “from address” do not clearly indicate your brand, test using your brand
name in the subject line.
• Action: Test the use of active verbs to elicit an open. Time sensitive language has proven to
perform well for limited time only offers and reminder messages. For example:
o “Two Days Left for Our Summer Sale”
o “See What’s New This Summer – Before It’s Too Late”
• Curiosity: Everyone is competing in the inbox. Email volume continues to rise and it is important
that your campaigns stand out in the crowd. Language that peaks your subscriber’s curiosity can
have a great impact on increasing open rates.
• Personalization: If the quality of your data is high, CheetahMail recommends the use of first
name personalization in subject lines. First name personalization may be a particularly good
strategy to paid subscriptions, invitations, special sales/messaging of certain customer groups
(such as best customers)
• Relevance: Never forget the individuality of your subscribers. Subject lines can try and speak to
the interests of your subscribers based on user preferences, purchase and/or web/email
behavioral data
Subject Lines and Deliverability:
Deliverability is not an exact science. While there are a variety of best practices we recommend to
decrease the possibility of an email triggering a spam filter, it is not possible to provide an absolute
solution. There are many reasons an email could be filtered as well as variations of spam filters in the
marketplace each with their own unique filtering algorithms. In addition to varying ISP filtering procedures,
preferences for spam filters may also be set at the user level and can vary from person to person.
CheetahMail’s years of experience have afforded us the ability to identify general best practices which
can guide you in your quest for improving deliverability. This document includes words, phrases and
symbols to avoid because they are generally known to trigger spam filters. However, we strongly advise
all clients to work with their account management team to test any word that they tend or would like to
use.
Experian CheetahMail
29 Broadway, 6th Floor, New York, NY 10006 • T 212 809 0825 • F 212 809 6378 • www.cheetahmail.com 3
Words:
The following are words that CheetahMail does not recommend using in subject lines:
• Manage
• Control
• No-Cost
• Relax
• Mortgage
• Vote
• Thousands
• Home
• Republicans
• Democrats
• Income
• Loan
• Fun
• Win
• XXX
Symbols:
The following are symbols or words that CheetahMail recommends testing the use of in subject lines:
• Free
• Question Marks (?)
• Dollar Signs ($)
• Exclamation Points (!)
• Percentage Signs (%)
• Exclusive
• Limited Time Only
2
Phrases:
The following are phrases that CheetahMail recommends avoiding within the content of your email
messages:
Experian CheetahMail
29 Broadway, 6th Floor, New York, NY 10006 • T 212 809 0825 • F 212 809 6378 • www.cheetahmail.com 4
• “Satisfaction Guaranteed”
• "One-Time Mailing"
• "Do Not Respond To This Email"
• "In Compliance With"
• "Including $$$ anywhere in the message or header"
• "Millions of dollars"
• "Direct email"
• "Bulk Mail"
• “If this message has reached you in error”
• “Click here to be removed”
• “100% Free”
• “Information you requested”
• “Call Toll Free”
• “1-800”
• “Visit our website”
• “Lose Weight”
• “Free Cruise”
• “Your Time and Interest”
• “Free Gift”
• “Free Consultation”
• “Respond Now”
• “Apply Now”
• “Financial Freedom”
• “Eliminate Debt”
• “Free Membership”
• “ad”
• “Earn $”
• “Double your income”
• “Extra Income”
• “Fast Cash”
• “Financially Independent”
• “Homebased Business”
• “Increase Sales”
• “Incredible Deal”
Experian CheetahMail
29 Broadway, 6th Floor, New York, NY 10006 • T 212 809 0825 • F 212 809 6378 • www.cheetahmail.com 5
• “Information you requested”
• “Opportunity”
• “Weight Loss”
• “Save $”
• “Online Marketing”
• “Make $”
• “Web Traffic”
• “Internet Market”
• “Call now”
• “Fax in your order”
• “This is an advertisement”
• 800 or 888 phone numbers
Experian CheetahMail
29 Broadway, 6th Floor, New York, NY 10006 • T 212 809 0825 • F 212 809 6378 • www.cheetahmail.com 6