Even experienced marketers sometimes stumble when it comes to email. Between automation, deliverability, and content strategy, there are countless moving parts and small missteps can quietly reduce engagement, conversions, or sender reputation.

That’s why it’s worth pausing from time to time to review what might be holding your campaigns back. Here are some of the most common mistakes when auditing email strategies, and what you can do to fix them.

1. Sending to people who didn’t opt in

Buying lists or uploading harvested addresses looks like a shortcut but ends badly: higher bounces, spam complaints, and damaged sender reputation. Use clear opt-in forms and incentive-driven signups (discount, download). If you inherit a list, run a re-permission and clean-up campaign before you mail.

How to fix it:

  • Offer a simple signup incentive and clear value.
  • Run a re-permission campaign for inherited contacts.
  • Never import a purchased list into active sends without permission checks.

2. Ignoring deliverability basics (authentication, warming, list hygiene)

Technical setup matters. Missing SPF/DKIM/DMARC, sudden large-volume sends, or a flooded list of bounces will get your mail throttled or routed to spam. New IPs should be warmed gradually, and your lists need regular pruning. These are non-negotiable hygiene steps.

How to fix it:

  • Configure SPF, DKIM and DMARC correctly.
  • Warm new IPs and ramp volume slowly.
  • Remove hard bounces and long-inactive addresses quarterly.

3. Treating every subscriber the same (no segmentation)

“Batch-and-blast” emails still happen too often. Without segmentation your messages will feel irrelevant and get ignored. Strategic segmentation (behavioral, demographic, purchase history) consistently increases clicks and conversions. But beware of both over-segmenting subscribers into too many tiny groups.

How to fix it:

  • Start with 3–4 practical segments: new subscribers, recent buyers, inactive users, and VIPs.
  • Use behavior triggers (cart abandonment, browse) for timely messages.
  • Measure which segments drive revenue and double down.

4. Relying on open rates as the main KPI

Because many mail clients (notably Apple Mail) now mask opens, open rates are noisy and unreliable. Focus instead on clicks, conversions, inbox placement and revenue-per-email. Design experiments around actions people take, not whether a tracking pixel fired.

How to fix it:

  • Track CTR, conversion rate and per-email revenue.
  • Use click-based triggers for automations rather than “non-opener” logic.
  • Use inbox-placement tools or seed lists to check deliverability.

5. Bad subject lines and weak preview text

Subject lines that overpromise, use spammy words, or are unclear will suppress engagement. Preview text is free real estate: use it to clarify value or complete the subject line. A/B test short, curiosity-driven vs. clear benefit-focused lines to learn what your audience prefers.

How to fix it:

  • Keep subject lines short and benefit-led.
  • Use preview text as a second subject line (not redundant).
  • Test with small samples before sending to the full list.

6. Poor mobile design and long overloaded emails

Most people open email on phones. If your email is wide, text-heavy, or has tiny CTAs, readers won’t convert. Keep layouts single-column, CTAs obvious, and links limited. Constant Contact’s analysis shows that too many links don’t increase clicks and can dilute focus.

How to fix it:

  • Use single-column, responsive templates.
  • Make the CTA above the fold and repeat it once more.
  • Limit links to the 1–3 most important actions.

7. No testing or post-send analysis

Sending without testing (render checks, spam tests, link checks) is asking for trouble. And if you don’t analyze results, you’ll repeat the same mistakes. Make testing and a 72-hour post-send review part of your checklist.

How to fix it:

  • Always send test emails to multiple devices and clients.
  • Run a spam-filter check before the campaign goes live.
  • After send: review CTR, conversions, unsubscribes and complaints — then iterate.

Summary: a short checklist to fix today

  • Set up SPF/DKIM/DMARC and warm IPs.
  • Start with 3–4 real segments; use behavior triggers.
  • Stop optimizing for opens — optimize for clicks & revenue.
  • Use responsive design, clear CTAs, and test before sending.

Fixing these mistakes usually doesn’t require new tools or big budgets, just a few disciplined processes and the right priorities. Get these fundamentals in place, and your next campaigns will reach more inboxes, get more clicks, and convert better, all while maintaining a strong sender reputation and staying far away from the spam folder.