Email campaign best practices

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Email campaign best practices

Last updated October 19, 2026 19:38

Make your campaigns compelling, readable, and deliverable.

How you compose and style your email campaigns depends on your brand and goals. Use these tips to send successful campaigns, no matter how you define success.

Attend a webinar

Sign up for our Engage Your Audience with Email Campaigns webinar where we show you how to use Email Campaigns, Squarespace’s built-in email marketing tool, to grow and engage your audience. You’ll learn how to build mailing lists, create and send campaigns, and measure campaign performance with our analytics tools.

Write your subject line and preview text

Your subject line and preview text are your first impression, and can inspire someone to open and read your email. Ensure this text is vivid and compelling. Experiment with different types of subject lines and review your analytics to find out which ones work for your audience.

Be specific and concise

Be specific. “We're opening a store in SoHo!” is better than “Big news!” Short, focused text helps readers understand your message. The subject line can be up to 75 characters.

Give readers a reason to open

Think about the benefit to the reader. What would make it worth their time to click through and read your campaigns? Promote sales or discounts. Ask a question to encourage readers to open the email to find out more.

Keep your text accurate

Ensure your text is accurate. This keeps your subscribers' trust, and may help you meet legal requirements like CAN-SPAM, CASL, and PECR. Avoid a subject line that promises something the campaign doesn't deliver.

Draft your email

Keep your campaign short, focused, and consistent with the rest of your brand. A campaign built around one topic and one next step is easier for readers to act on.

Focus on one topic and one action

Include one clear call to action, like a link to your site or a product they can buy. Ask yourself: What's the one thing I want everyone reading this campaign to do?

Keep your branding consistent

Use the same language and tone you use on your website. Include a link to your site, such as a text link or a button. Site logos link to your site automatically.

Style your campaign

Keeping your style simple helps your readers focus on your content and message.

Use color to draw attention

Keeping your style simple helps your readers focus on your content and message. Use pops of color to draw attention to your call-to-action, like a brightly colored button. A light background color with dark text is usually easiest to read.

Style and design guides

We have several guides about style and design. Although they focus on website design, most of the tips apply to email campaigns too. Review them for guidance on imagery, layout, and accessibility:

Add images

Images are a great way to set the tone and draw in readers. These guidelines cover file naming, formats, size limits, and how images appear when a reader's email provider hides them. Follow them for each image you add to a campaign.

Name your image files for alt text

Your image name becomes its alt text, so ensure the file name describes the image. Only use letters, numbers, underscores, and hyphens in the file name.

Use a supported file format

Use .jpg, .gif, or .png format only. Campaigns don't support Webp images. Convert any unsupported files before you upload them.

Stay within file size and resolution limits

For best results, use image files under 500 KB. The limit for a single image upload is 20 MB. The image size limit is 120 MP (megapixels). Smaller files load faster for your readers.

Pair images with text

Include text to help get the message across. Some email providers hide images, so add text in your campaign that shares your message even if the image is missing. This way, your message still lands when images don't display.

Keep image dimensions consistent

If a section has more than one image, use images with the same size. Consistent dimensions keep your layout even across sections. Your images also resize for each reader's device. Email Campaigns' built-in responsive design resizes your images based on the visitor's screen.

Build and maintain your mailing lists

It can be tempting to add as many users to your list as possible, but you'll get the best results from people who signed up voluntarily and are excited to engage with your content. A healthy mailing list has low unsubscribe rates and doesn't include invalid, incorrectly formatted, or fake addresses. Follow these best practices to keep your lists healthy over time.

Only add people who opted in

Adding people without their permission can annoy them, cause filters to mark you as spam, and may violate legal restrictions like CAN-SPAM, CASL, or PECR. It also violates our Acceptable Use policy and may result in your account being disabled. Never use a mailing list that you bought or that someone gave you, because those subscribers haven't said they want to get your email.

Add signup areas to your site

Add areas on your site where people can sign up for your newsletters. Visitors who subscribe this way have told you they want to hear from you.

Don't gate content or run giveaways to collect addresses

If you ask visitors for an email address before they can see or download content, it can cause them to use fake email addresses. Don't use giveaways that require an email address for entry to collect addresses for your mailing lists. These recipients may not recognize you as a sender and could mark your campaign as spam.

Clean your list before you import it

When exporting a mailing list from another service provider, like Mailchimp, ensure it only includes active, engaged subscribers. Before importing into Email Campaigns, remove any unsubscribed email addresses (including “culled” or “cleaned” addresses) from the list. If you have a large list that isn't performing well, consider using a list cleaning service like BriteVerify or ZeroBounce.

Remove old, fake, and duplicate addresses

If you've had your list for a long time, it may have many old or unused email addresses. Consider sending an email inviting your subscribers to resubscribe to a new list, and then delete the old one. This ensures that people who aren't interested in your content don't get it. Occasionally go through your mailing list and delete any emails that are clearly fake, invalid, or duplicates. Even when you're following best practices, you might get invalid signups from spambots, people making mistakes, and people trying to send you inappropriate or unsolicited information.

If your mailing list upload fails

Squarespace Support can't troubleshoot the contents of a mailing list. If you see an “Upload Failed” message, review the sections above and edit your list to ensure it's healthy. Remember, you shouldn't send campaigns to anyone who hasn't agreed to receive emails from you.

Ensure the Unsubscribe option is visible and easy to use.

Squarespace campaigns include an unsubscribe link that you can’t remove. You don't need to add one.

Don't add more unsubscribe links manually, because they won't work, which may cause subscribers to mark your campaigns as spam.

Why easy unsubscribes help you

Allowing people to unsubscribe is required, but it's also smart. People unsubscribe for many reasons, and not always because they don't enjoy the content. For example, they may already get your newsletter at a different address, or may be taking a break from all newsletters for a while. If you let them unsubscribe easily, they're more likely to resubscribe in the future.

If the unsubscribe link is hard to see, people may report you as spam instead of unsubscribing, which makes it more likely that future campaigns to other subscribers get marked as spam. Spam reports affect the campaigns you send to everyone on your list, not only the reader who filed the report. Learn more about email campaign unsubscribes.

Ensure the business name and address in the footer is a real address. Anti-spam and privacy laws like CAN-SPAM require this. It also helps build credibility with customers, and can help your campaign avoid spam filters. For more information, including what to do if you don't have a business name or business address yet, visit Adding your business name and address.

How to avoid spam filters

If an email goes into a spam folder or bounces, the reader never sees it. Confirming who you are as a sender, and who has agreed to hear from you, does the most to get your campaign into the Inbox. Here are our top tips to avoid spam filters:

  • Verify your email.
  • Use a custom email address and verify its domain.
  • Only include people who've confirmed they want to receive your campaigns.

Design for dark mode

Dark mode is a popular display setting that uses light text on a dark background, which can reduce eye strain. Squarespace Email Campaigns has no built-in way to style for dark mode, but you can follow a few tips to help your emails display clearly in both light and dark mode.

Images and logos

Use transparent images, which adapt better to light and dark backgrounds. If your logo is black and you're using a transparent image, add a white stroke to the black text to make it easier to read. Without the stroke, black lettering can disappear against a dark background.

Font and button color

Use dark grey (#333333) and lighter white (#F8F8F8) instead of pure black and white text, so the text is easier to read. Choose button colors that have enough contrast against both light and dark backgrounds. Enough contrast keeps your call to action visible either way.

Test your campaign in both modes

Consider testing your emails in both light and dark mode across devices. To do this, change your device settings and send yourself test emails. Comparing the same campaign in both settings is the quickest way to catch a logo or button that doesn't hold up.

Review any anti-spam and privacy laws for your country and the country of anyone you're sending campaigns to, such as CAN-SPAM, CASL, or PECR. Violating these laws can result in fees and other penalties. These laws also shape the requirements covered elsewhere in this guide, including your unsubscribe link and your legal address.

Review and improve your campaigns

Follow these tips to hone your email marketing strategy.

Keep your messaging consistent across all emails

Think about other emails your subscribers are getting from you, like commerce notifications. Keep your tone and branding consistent across all these messages. Subscribers should recognize you whether they're reading a newsletter or an order confirmation.

Send a test before every campaign

Always send a test email before sending your campaign. If possible, mail the test to a few people to get their feedback. Reviewing your campaign in an inbox, rather than in the editor, is the best way to catch broken links and formatting issues.

Review your analytics after you send

After sending a campaign, review how it performed and compare that to past campaigns. Over time you'll learn what works best for your audience. Your analytics also show which subject lines and content earn the most opens and clicks.

Run an A/B test

Consider setting up an A/B test to find out what content works best for your subscribers. An A/B test sends different versions of a campaign so you can compare the results side by side. Use what you learn to shape the campaigns you send next.

Experiment with your send timing

Experiment with when you send your campaigns. For example, do your subscribers check email first thing in the morning? In the evening before bed? Do they act differently with emails sent on weekdays vs. weekends? Follow your analytics on each campaign to find out what works best.

Personalize with mail merge tags

Use mail merge tags to add personalized content for each subscriber, like their name. Personalizing your campaigns makes them feel less generic and may lead to a higher open rate. You can add a tag anywhere you'd otherwise write a subscriber's details by hand.

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Email campaign best practices