What is an email header?

An email header is the top part of an email. It contains important information, like the sender and recipient’s email addresses and the email date and subject. It also includes any content preceding the email’s text, such as images, contact info, or a company logo.

By clarifying who the email is from and what it contains, headers help recipients determine whether the email is genuine or a phishing attempt.

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What does an email header contain?

These are the essential parts of every email header:

  1. Header information
  2. Subject line
  3. Header content

Ensuring your email header contains all components helps leave a good first impression. If the email header isn’t properly organized and well-designed, your subscribers could skip reading your emails altogether.

Header information

Header information is the mandatory technical information in the fields that someone sees after opening an email. The fields contain data such as:

  • Sender information: Indicating the sender’s email address, this section confirms the sender is legitimate and the email isn’t a scam.
  • Recipient information: This field shows one or more email addresses that received the email.
  • Date: The date field shows the day, month, year, and time the email was sent.

The CAN-SPAM Act dictates the rules regarding these essential elements, and not following them in your emails could result in hefty fees. Make sure that you’re using the right tool in your email marketing efforts, and that you’re not deceiving your recipients.

Subject line

Your audience sees your email’s subject line before even opening the email, so it’s important to make it engaging enough to invite them to keep reading.

Here are a few best practices for creating the perfect subject line for your emails:

  • Capture the essence of your email: Don’t use vague or misleading text in your subject line. Keep the text concise and clear so that it’s easy to understand what the email is about just by reading the subject line.
  • Keep it short: Make your subject line short and catchy by keeping it under 40–50 characters.
  • Align the tone with the email’s goal: Subject lines can be funny, convey urgency, or harness fear of missing out (FOMO) to engage recipients. Choose your ideal subject line tone based on your email’s goal.
  • Watch out for spammy words: Avoid words that could trigger spam filters and tank email deliverability. These may be terms like “cash,” “credit,” “income,” or “deal.”
  • Make recipients feel special: Personalize your subject line to capture the recipient’s attention and increase your email open rate.

💡 Pro tip: Advanced marketing automation tools like Klaviyo offer AI assistance for writing personalized and engaging subject lines.

Header content

Header content takes up the area above the email’s copy. Although it’s not essential, adding header content helps you personalize your emails and improve your subscribers’ experience.

Depending on your email content and brand details, your header content can include elements such as:

  • Logo
  • Banner
  • Contact info
  • Menu

Here are a few best practices to maximize the potential of this area:

  • Focus on versatility: Create a versatile header that you can easily adapt to different types of emails.
  • Keep it short and sweet: Don’t make your header longer than the email copy—it needs to complement the email’s content, not steal its spotlight.
  • Highlight your brand: Add your company’s logo and contact info in the header, and use your brand’s colors, font, and slogan (if you have one). This will help the recipients easily memorize your brand and confirm your emails’ legitimacy.
  • Add a menu: Guide your recipients to take specific actions from your email by creating a functional menu in your header. Make sure the menu corresponds to the email’s content—for example, if the email promotes a product, create a menu that redirects your recipients directly to this item on your website.

Send smart emails that convert

Klaviyo is a marketing automation tool that eliminates the stress of designing email headers with its email templates. With over 100 customizable templates, Klaviyo makes it easy to not only create your headers, but also add images, logos, and functional menus to your emails. After creating a header, you can save it and add it to your future emails.

Email templates are only a drop in the bucket of Klaviyo’s email marketing features:

Ready to create catchy email headers and launch your campaigns? Sign up for Klaviyo and create personalized messages that convert.

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