Email Marketing

Best Practices:

First impressions are crucial in email marketing; subject lines attract users, boost open rates, prevent emails from being deemed spam, and ultimately dictate ROI across email marketing efforts, as the content becomes irrelevant unless subscribers view the email in the first place. 

Personalising subject lines increases open rates by 22% (Saleh, 2016), signifying the importance of appearing personable as a business. Methods to do this can involve using the subscriber's name to demonstrate intent and imply that your service or product feels tailored to your consumer. Additionally, the subject line must accurately and concisely describe the content so subscribers can assess its value. "Subject lines under 70 characters achieve the highest open rates", (MailMendTeam, 2025) supporting this idea.

Optimising email campaign components can be achieved through A/B testing, which is available across email service providers. This allows different variants of the same email to be sent to your audience. You can test metrics such as CTRs, sharing and forwarding rates, and conversion rates to determine how best to display your campaign. Elements such as the subject line, images, and links can all be used as variables to optimise this process. Statistically, "One out of eight A/B tests drives significant change", (Blagojevic, 2025) showing how this practice effectively facilitates growth for email campaigns.

 

Furthermore, segmenting your subscriber list based on the information they have provided helps determine which content to include in emails, providing a more direct message. As a result, this drives engagement and boosts your campaign's ROI. Businesses generated 17 times the revenue with two or more segments than those with a single segment (Blankenship, 2023). Demographics to segment by could include age, goals, daily life, gender, and their stage in the buyer's journey. By utilising buyer personas, emails are refined further and, when combined with the previously discussed personalisation efforts, provide real value to an audience.

With these factors considered, data protection must not be neglected. When collecting data for email lists, ensuring sign-up forms are GDPR-compliant enables the lawful collection of personal information (Bravo, 2024). Using double opt-in gives users the option to confirm their subscription after signing up, provides proof of sign-up, and reduces hard bounce rates caused by invalid email addresses (Team, 2024). Additionally, verification confirms that emails are delivered, thus increasing the potential for sales. These steps are essential because they enhance the reputation and validity of your emails, helping you avoid landing in the spam folder. Offering an opt-out option for your subscribers is also vital, as it is the law. Whilst it may seem negative for businesses, it helps reputation, engagement, and ROI, and allows insight into why your campaign may not be effective for a particular subscriber (Syed Balkhi, 2025). Opting out helps streamline your overall efforts, making your email marketing more effective.

Mistakes to avoid:

Buying a mailing list is a mistake in email marketing because it increases the risk of landing in the spam folder, as the audience is unfamiliar with your business. As mentioned in the data protection section, bounce rates would likely increase if you did this, which would decrease your reputation and often result in being blocked from sending emails. ESPs also do not allow the use of purchased lists, and without their assistance, sending email campaigns becomes far more tedious (Campmonauthor, 2018).

To ensure emails are accessible regardless of network connection strength, they should not be written solely in HTML. You should provide viewers with the option to view the email in plain text, even though it may appear less engaging; it loads faster and can feel more personal. Using only HTML is also less effective than plain text: "the HTML email version had a 21% lower clickthrough rate, and combined with the open rate the email had 51% fewer clicks" (Shah, 2021), according to A/B tests conducted by HubSpot.

Furthermore, images must be used appropriately throughout the email and should not hinder the message or viewing experience. Whilst they are great to create context and familiarity with your brand, subscribers must navigate CTAs and text effectively throughout. Make sure images are relevant and use linked images rather than attached images to improve render times and prevent potential flagging that may increase bounce rates due to file size (Krishnamurthy, 2025).

Reference list

Blagojevic, I. (2025). 17 Crucial A/B Testing Statistics For 2026 - 99firms. [online] 99Firms.com. Available at: https://99firms.com/research/ab-testing-statistics/#gref [Accessed 4 Jan. 2026].

Blankenship, W. (2023). The Drip Marketing Automation Report 2024. [online] Drip.com. Available at: https://www.drip.com/blog/marketing-automation-report [Accessed 4 Jan. 2026].

Bravo (2024). GDPR in Email Marketing: How to Be Compliant and Avoid Fines. [online] Brevo. Available at: https://www.brevo.com/blog/gdpr-email-marketing/?utm_source=adwords&utm_medium=cpc&utm_content=Email&utm_extension=&utm_term=gdpr%20email&utm_matchtype=p&utm_campaign=21495448774&utm_network=g&km_adid=669691985030&km_adposition=&km_device=c&utm_adgroupid=165124809756&gad_source=1&gad_campaignid=21495448774&gbraid=0AAAAADjx0RaN-KEEhVIFPYI1MEtspsek-&gclid=Cj0KCQiAvOjKBhC9ARIsAFvz5lgbnBPgggPyTJvk3lGps4aLZTlAooNiE29aJnR6yoz32I8rzED30toaAnILEALw_wcB [Accessed 4 Jan. 2026].

campmonauthor (2018). Don't Buy Your Email Lists: Here's Why. [online] Campaign Monitor. Available at: https://www.campaignmonitor.com/blog/email-marketing/why-purchased-email-lists-are-a-huge-no-no-for-your-email-marketing/ [Accessed 4 Jan. 2026].

Krishnamurthy, K. (2025). Do Images in Emails Hurt Your Campaigns? Here's What We Found. [online] Luru.app. Available at: https://www.luru.app/post/do-images-in-emails-hurt-your-campaigns-heres-what-we-found#The%20Numbers [Accessed 4 Jan. 2026].

MailMendTeam (2025). 29 Subject Line Effectiveness Statistics Every E-commerce Brand Needs to Know - Mailmend: The Best Email Deliverability Software. [online] Mailmend.io. Available at: https://mailmend.io/blogs/subject-line-effectiveness-statistics [Accessed 4 Jan. 2026].

Saleh, K. (2016). Email Subject Lines – Statistics and Trends. [online] Invesp. Available at: https://www.invespcro.com/blog/email-subject-lines-statistics-and-trends/ [Accessed 4 Jan. 2026].

Shah, N. (2021). Plain Text vs. HTML Emails: Which Is Better? [New Data]. [online] blog.hubspot.com. Available at: https://blog.hubspot.com/marketing/plain-text-vs-html-emails-data [Accessed 4 Jan. 2026].

Syed Balkhi (2025). Email Opt-Out: Definition, Benefits & Best Practices [2025]. [online] Email Marketing Automation Platform for Thriving Businesses. Available at: https://moosend.com/blog/email-opt-out/ [Accessed 4 Jan. 2026].

Team, C. (2024). The Complete Guide to GDPR Email Marketing - CookieYes. [online] CookieYes. Available at: https://www.cookieyes.com/blog/gdpr-email-marketing/ [Accessed 4 Jan. 2026].