How to Write A Good Subject Line for Email

Crafting the Perfect Email Subject Line: A Technical Guide

The email subject line is your first, and often only, chance to make a strong impression. In the digital age, where inboxes are overflowing, a well-crafted subject line can be the difference between an email being opened and read, or being immediately deleted or marked as spam. This article will delve into the technical aspects of creating compelling email subject lines, exploring strategies to optimize them for engagement, deliverability, and overall success.

Understanding Email Deliverability and Subject Line Impact

Email deliverability is the measure of your emails successfully reaching the intended recipients’ inboxes. It’s not just about avoiding hard bounces (permanent delivery failures); it’s also about preventing your emails from landing in the spam folder. Subject lines play a crucial role in this process, influencing both spam filters and recipient behavior. Understanding how these factors interact is paramount to crafting effective subject lines.

Spam filters are sophisticated systems that analyze various email elements, including the subject line, to determine if an email is legitimate or spam. These filters use a combination of rule-based and machine learning algorithms. Rule-based filters often look for specific keywords or phrases associated with spam, while machine learning algorithms analyze patterns and learn from past email behavior. A subject line containing words like “free,” “guarantee,” or excessive punctuation (e.g., “!!!”) can trigger spam filters and prevent your email from reaching the inbox.

Recipient engagement, specifically open rates and click-through rates (CTR), also impacts deliverability. Email providers like Gmail and Outlook track how recipients interact with your emails. If a significant number of recipients mark your emails as spam or simply delete them without opening, your sender reputation will suffer, leading to lower deliverability rates. A misleading or irrelevant subject line can lead to disengaged recipients and negatively impact your sender reputation. Therefore, your subject line must be both enticing and accurate, accurately reflecting the content of the email.

Technical Considerations for Spam Filters

To avoid triggering spam filters, consider these technical aspects when crafting your subject lines:

• Keyword Avoidance: Avoid using common spam trigger words such as “free,” “guarantee,” “opportunity,” “urgent,” “cash,” and excessive dollar signs ($$$). Use a thesaurus to find alternative wording.
• Punctuation and Special Characters: Refrain from using excessive punctuation marks (!!!, ???) or special characters (@, #, %, ^, &). These are red flags for spam filters.
• Character Encoding: Ensure your subject line uses proper character encoding (UTF-8 is recommended). Incorrect encoding can result in garbled text, which can trigger spam filters.
• Capitalization: Avoid using all caps in your subject line. It can be perceived as shouting and is often associated with spam.
• HTML Formatting: Keep your subject line plain text. Avoid embedding HTML formatting or images in the subject line. Most email clients don’t support it, and it can trigger spam filters.

Monitoring Sender Reputation

Maintaining a positive sender reputation is crucial for email deliverability. Here’s how to monitor and improve it:

• Use Sender Authentication Protocols: Implement SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) records. These protocols verify that your emails are sent from authorized servers and help prevent email spoofing.
• Monitor Blacklists: Regularly check if your domain or IP address is listed on any email blacklists. Tools like MXToolbox and Spamhaus can help you identify blacklist issues.
• Analyze Bounce Rates: Monitor your hard and soft bounce rates. High bounce rates can indicate outdated email lists or deliverability problems. Clean your email lists regularly to remove invalid or inactive addresses.
• Track Engagement Metrics: Monitor your open rates, click-through rates, and spam complaints. Low engagement rates and high spam complaints can negatively impact your sender reputation.
• Use Feedback Loops: Implement feedback loops with major email providers like Gmail and Outlook. This allows you to receive reports of spam complaints from their users, enabling you to identify and address deliverability issues proactively.

Example 1: SPF Record Configuration (DNS Zone File):

yourdomain.com.  TXT  "v=spf1 a mx include:your-email-service.com ~all"

This SPF record specifies the authorized mail servers for your domain. Replace `your-email-service.com` with the domain of your email sending service. This helps prevent email spoofing and improves deliverability.

Example 2: DMARC Record Configuration (DNS Zone File):

_dmarc.yourdomain.com.  TXT  "v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com; ruf=mailto:dmarc-forensic@yourdomain.com;"

This DMARC record defines how email receivers should handle emails that fail SPF or DKIM checks. `p=none` means no action is taken (monitoring only), `rua` specifies the email address for aggregate reports, and `ruf` specifies the email address for forensic reports. You should transition to `p=quarantine` or `p=reject` after monitoring.

By carefully crafting your subject lines and actively managing your sender reputation, you can significantly improve your email deliverability and ensure that your messages reach their intended audience.

Leveraging Psychology and Persuasion in Subject Lines

Beyond the technical aspects of avoiding spam filters, understanding the psychology of persuasion is crucial for crafting subject lines that resonate with your audience and drive opens. By leveraging psychological principles, you can create subject lines that tap into recipients’ desires, fears, and motivations, making your emails more compelling and likely to be opened.

Several psychological principles can be effectively applied to email subject lines:

• Scarcity: People are more likely to take action when they believe something is in limited supply. Subject lines that highlight scarcity can create a sense of urgency and encourage recipients to open the email immediately.
• Urgency: Similar to scarcity, urgency creates a sense of time sensitivity, prompting recipients to act quickly. Subject lines that emphasize deadlines or limited-time offers can be highly effective.
• Curiosity: Humans are naturally curious. Subject lines that pique curiosity can entice recipients to open the email to learn more. However, it’s important to strike a balance between creating curiosity and being misleading.
• Social Proof: People are influenced by the actions and opinions of others. Subject lines that highlight social proof, such as testimonials or the number of users who have benefited from a product or service, can increase credibility and trust.
• Personalization: Addressing recipients by name or referencing their past behavior can make them feel valued and increase engagement. Personalized subject lines can demonstrate that you understand their needs and interests.
• Loss Aversion: People are more motivated to avoid losses than to gain something of equal value. Subject lines that highlight potential losses can be highly effective in driving action.

Examples of Psychological Principles in Action

Here are some examples of how to apply these psychological principles in email subject lines:

• Scarcity: “Only 5 Seats Left: Exclusive Marketing Workshop”
• Urgency: “Last Day to Save 20% on All Products”
• Curiosity: “The Surprising Secret to Boosting Productivity”
• Social Proof: “Join 10,000+ Happy Customers – See What They’re Saying”
• Personalization: “John, We Have a Special Offer Just for You”
• Loss Aversion: “Don’t Miss Out: Your Free Trial Ends Tomorrow”

Example 1: A/B Testing Subject Lines with Scarcity and Urgency:

Imagine you’re promoting a webinar. You could A/B test these two subject lines:

• Subject Line A: “Register for Our Upcoming Webinar”
• Subject Line B: “Limited Seats! Register Now for Our Webinar (Ends Friday)”

Subject Line B incorporates both scarcity (limited seats) and urgency (ends Friday). Track the open rates and registrations for each subject line to determine which performs better with your audience. Tools like Mailchimp, Sendinblue, and ConvertKit offer built-in A/B testing features.

Example 2: Personalization using Merge Tags:

Most email marketing platforms allow you to personalize subject lines using merge tags. For instance, in Mailchimp, you can use the `*|FNAME|*` tag to insert the recipient’s first name:

{{First Name}}, Check out these deals!

The actual subject line sent to a recipient named “Alice” would be: “Alice, Check out these deals!”. Remember to ensure your email list contains accurate first name data for effective personalization.

By understanding and applying these psychological principles, you can significantly enhance the effectiveness of your email subject lines and drive higher open rates, click-through rates, and conversions.

Technical SEO for Email Subject Lines

While the term “SEO” is primarily associated with website optimization for search engines like Google, the principles of search engine optimization can also be applied to email subject lines. Optimizing your subject lines for “email search” within the inbox and for general clarity can improve engagement and overall campaign performance. This involves considering factors like keyword usage, character limits, mobile optimization, and A/B testing.

Just as keywords are crucial for website SEO, they are also important for email subject lines. Including relevant keywords can help recipients quickly understand the content of your email and determine if it’s relevant to their interests. This is particularly important for subscribers who use the search function within their email client to find specific emails.

Character limits are another important consideration. Most email clients display only a limited number of characters in the subject line. If your subject line is too long, it will be truncated, potentially obscuring important information or the call to action. Mobile devices, with their smaller screens, further exacerbate this issue. Aim for a subject line length of around 40-60 characters to ensure that it’s fully visible on most devices.

Mobile optimization is essential in today’s mobile-first world. A significant percentage of emails are opened on mobile devices, so it’s crucial to ensure that your subject lines are mobile-friendly. This means keeping them concise and front-loading the most important information. Avoid using long or complex words that may be difficult to read on a small screen.

A/B testing is a powerful technique for optimizing your subject lines. By testing different variations of a subject line, you can identify which version performs best in terms of open rates, click-through rates, and conversions. A/B testing allows you to make data-driven decisions about your subject lines and continuously improve their effectiveness.

Implementing Technical SEO Strategies for Subject Lines

Here’s how to implement these technical SEO strategies for your email subject lines:

• Keyword Research: Identify the keywords that are most relevant to your target audience and the content of your email. Use keyword research tools to find popular and relevant keywords.
• Character Limit Optimization: Keep your subject lines concise and within the recommended character limit of 40-60 characters.
• Mobile Optimization: Prioritize mobile users by front-loading the most important information in your subject lines.
• A/B Testing: Regularly A/B test different variations of your subject lines to identify which perform best. Test different keywords, lengths, and calls to action.
• Analyze Results: Track the performance of your subject lines and analyze the results to identify patterns and trends. Use this data to inform your future subject line strategies.

Example 1: Keyword Research using Google Keyword Planner:

Let’s say you’re promoting a new project management software. You can use Google Keyword Planner to identify relevant keywords. After entering seed keywords like “project management,” “task management,” and “team collaboration,” the tool will provide a list of related keywords, their search volume, and competition level. You might find keywords like “agile project management software” or “free project management tools” that you can incorporate into your subject lines.

Example 2: A/B Testing Subject Lines in Mailchimp:

Mailchimp allows you to easily A/B test different subject lines. When creating a campaign, select the “A/B Test” option. You can then specify two different subject lines, a percentage of your list to send each version to, and the winning metric (e.g., open rate or click-through rate). Mailchimp will automatically send the winning subject line to the remaining subscribers after a specified period.

By applying these technical SEO strategies to your email subject lines, you can improve their visibility, relevance, and overall performance, leading to higher engagement and better campaign results.

Monitoring and Analyzing Subject Line Performance with Analytics

Crafting effective email subject lines is an iterative process. It’s not enough to simply create a subject line and send it out. You need to continuously monitor and analyze the performance of your subject lines to identify what works and what doesn’t. By tracking key metrics and analyzing the results, you can refine your subject line strategies and improve your overall email marketing performance.

Several key metrics can be used to assess the performance of your subject lines:

• Open Rate: The percentage of recipients who opened your email. This is the most basic metric for measuring subject line performance. A higher open rate indicates that your subject line was effective in capturing recipients’ attention and enticing them to open the email.
• Click-Through Rate (CTR): The percentage of recipients who clicked on a link within your email. This metric measures how engaging your email content is. A higher CTR indicates that your subject line effectively conveyed the value proposition of your email and motivated recipients to take action.
• Bounce Rate: The percentage of emails that could not be delivered. A high bounce rate can indicate issues with your email list or deliverability problems. Subject lines can indirectly affect bounce rates if they lead to spam complaints, which can negatively impact your sender reputation.
• Conversion Rate: The percentage of recipients who completed a desired action, such as making a purchase or filling out a form. This metric measures the ultimate effectiveness of your email campaign. Subject lines play a crucial role in driving conversions by attracting recipients’ attention and motivating them to take action.
• Spam Complaint Rate: The percentage of recipients who marked your email as spam. A high spam complaint rate can severely damage your sender reputation and negatively impact your deliverability. Misleading or irrelevant subject lines can lead to increased spam complaints.

Tools and Techniques for Monitoring and Analysis

Here are some tools and techniques you can use to monitor and analyze your subject line performance:

• Email Marketing Platform Analytics: Most email marketing platforms, such as Mailchimp, Sendinblue, and ConvertKit, provide built-in analytics dashboards that track key metrics like open rates, click-through rates, bounce rates, and conversion rates.
• Google Analytics: If you include links to your website in your emails, you can use Google Analytics to track website traffic and conversions generated by your email campaigns. Use UTM parameters to track specific email campaigns and subject lines.
• A/B Testing Tools: Use A/B testing tools to compare the performance of different subject line variations. Track the open rates, click-through rates, and conversion rates for each variation to identify the most effective subject lines.
• Segmentation: Segment your email list based on demographics, interests, and past behavior. Analyze the performance of your subject lines for each segment to identify what resonates with different groups of recipients.
• Heatmaps: Use heatmap tools to visualize how recipients interact with your emails. Heatmaps can show you which links are clicked most often and which areas of your email are most engaging.

Example 1: Tracking UTM Parameters in Google Analytics:

To track the performance of a specific email campaign and subject line in Google Analytics, add UTM parameters to the links in your email:

https://www.example.com/?utm_source=email&utm_medium=newsletter&utm_campaign=summer_sale&utm_content=subject_line_a

In this example, `utm_source` is set to “email,” `utm_medium` is set to “newsletter,” `utm_campaign` is set to “summer_sale,” and `utm_content` is set to “subject_line_a.” You can then track the traffic and conversions generated by this specific subject line in Google Analytics by filtering for the `summer_sale` campaign and `subject_line_a` content.

Example 2: Analyzing Open Rates in Mailchimp:

In Mailchimp, you can view the open rate for each email campaign on the campaign report page. This allows you to quickly identify which subject lines performed best in terms of attracting recipients’ attention. You can also compare the open rates of different campaigns to identify trends and patterns over time. Mailchimp also provides A/B testing reports where you can compare the performance of different subject line variations directly.

By consistently monitoring and analyzing your subject line performance, you can gain valuable insights into what resonates with your audience and continuously improve your email marketing strategies. This data-driven approach will help you craft more effective subject lines that drive higher open rates, click-through rates, and conversions.