Introduction
Email marketing continues to be one of the most cost-effective digital channels in 2025, delivering an average ROI of £38 for every £1 spent. But while the potential is huge, many UK businesses fail to unlock it due to avoidable mistakes.
In this blog, we outline the most common email marketing errors and how partnering with a professional email marketing agency like Finsbury Media can turn things around.
1. Sending to Unsegmented Lists
Not all subscribers are the same. Sending the same message to your entire database results in low engagement and high unsubscribe rates.
The Fix:
- Use segmentation to group subscribers by behaviour, location, or purchase history
- Create tailored content for each segment to boost relevance and open rates
2. Poor Subject Lines That Kill Open Rates
Your subject line is the first (and sometimes only) chance to make an impression. Weak or spammy subject lines can lead to immediate deletion.
The Fix:
- A/B test subject lines regularly
- Keep them concise, benefit-focused, and relevant
- Avoid excessive punctuation or ALL CAPS
3. Ignoring Mobile Optimisation
Over 60% of emails are opened on mobile devices. If your email doesn’t render correctly on a smartphone, it won’t get read.
The Fix:
- Use responsive email templates
- Test across devices before sending
- Keep content skimmable with clear CTAs
4. Overloading with Content or Links
Emails that are cluttered or try to do too much confuse readers and dilute your message.
The Fix:
- Focus on one clear goal per email
- Use white space and visuals strategically
- Limit to 1-2 CTAs to avoid distraction
5. Not Measuring or Acting on Results
Many businesses send emails but never analyse performance. Without data, you can’t improve.
The Fix:
- Track open rates, click-through rates, bounce rates, and conversions
- Use insights to refine timing, content, and segmentation
- Consider marketing automation for smarter delivery
FAQs
What is the most common email marketing mistake?
One of the most common mistakes is sending unsegmented, irrelevant emails to a large list. This leads to low engagement and high unsubscribe rates.
How often should I send marketing emails?
It depends on your audience, but consistency is key. Weekly or bi-weekly is common. Testing frequency and monitoring engagement metrics will help determine the sweet spot.
Why do my emails end up in spam?
This can happen due to poor sender reputation, spammy subject lines, or lack of proper authentication (like SPF and DKIM). A professional email marketing agency can help resolve this.
Should I use email automation?
Yes. Automation increases efficiency and ensures timely, relevant messaging. It’s especially useful for welcome series, abandoned cart reminders, and re-engagement campaigns.
What’s the benefit of hiring an email marketing agency?
An experienced email marketing agency like Finsbury Media brings strategy, creative, and technical expertise to help you avoid costly mistakes and maximise ROI.
Conclusion
Email marketing remains one of the most powerful digital tools – but only when done correctly. Avoiding common mistakes and embracing best practices is crucial for success in 2025.
Speak to a Finsbury Media email marketing expert to optimise your strategy, improve deliverability, and boost campaign performance today.
