Subject Line Best Practices (Rules 1-4)
Rule 1: Keep Subject Lines Under 50 Characters
47% of recipients open emails based on subject line alone. Subject lines under 50 characters have 12% higher open rates. On mobile (60% of opens), long subject lines get truncated. "Your February results are ready" (35 chars) beats "Here are all the amazing February email marketing results we compiled for you" (78 chars).
Rule 2: Avoid Spam Trigger Words
Words like "FREE," "GUARANTEE," "ACT NOW," "LIMITED TIME," and ALL CAPS trigger spam filters. Use them sparingly and never in combination. Instead of "FREE OFFER!!!", use "A gift for you" or "Complimentary access." Test your subject lines with a spam checker before sending.
Rule 3: Use Preview Text as a Second Subject Line
Preview text increases open rates by 15-25% when used strategically. Never let it default to "View this email in your browser." Use it to create curiosity, add context, or tease the content. Example: Subject "Your weekly tips" + Preview "Plus: a free template you can use today."
Rule 4: A/B Test Every Subject Line
A/B testing subject lines improves open rates by 20% on average. Test one variable at a time: length, tone, personalization, emoji, urgency vs curiosity. Send variant A to 20% of your list, variant B to 20%, then the winner to the remaining 60%. Most platforms automate this — GetResponse includes A/B testing on all plans.
Content Best Practices (Rules 5-9)
Rule 5: Follow the 80/20 Rule
80% of your emails should provide value (education, entertainment, inspiration). 20% should promote (sales, offers, product launches). If every email is a pitch, subscribers tune out. If every email is pure value, you leave revenue on the table. The 80/20 balance keeps subscribers engaged while driving revenue.
Rule 6: Use One CTA Per Email
Emails with a single CTA have 371% higher click rates than emails with multiple CTAs. Multiple CTAs create decision paralysis. Pick one action and make it the only clickable action. Repeat the same CTA 2-3 times if needed, but never offer different options in the same email.
Rule 7: Write for Scannability
The average attention span is 8 seconds. Subscribers scan before they read. Use short paragraphs (2-3 sentences), bullet points, bold key points, and clear headings. Subscribers should understand the email's purpose in 5 seconds of scanning. Keep marketing emails under 300 words.
Rule 8: Personalize Beyond First Name
First name personalization increases open rates by 26%. But deeper personalization — referencing past purchases, browsing behavior, or content downloads — increases click rates by 139% and conversion rates by 202%. Use behavioral data to tailor content: "Since you bought [Product], here is how to get the most out of it."
Rule 9: Use the P.S. Line
The P.S. line is the second most-read part of an email (after the subject line). 80% of readers scan to the bottom before reading the full email. Use the P.S. for your CTA, a deadline reminder, a bonus offer, or a personal note. "P.S. This offer expires Friday — don't miss out."
Design Best Practices (Rules 10-12)
Rule 10: Design Mobile-First
60% of emails are opened on mobile. Design for mobile first: single-column layout, 14-16px font size, large tap targets (44x44px), and images under 200KB. Test on iOS and Android before sending. If your email looks great on desktop but broken on mobile, 60% of subscribers will delete it.
Rule 11: Keep Image-to-Text Ratio at 40:60
Emails with too many images (60%+ image content) trigger spam filters. Keep the image-to-text ratio at 40:60. Use 1-3 images maximum. Always include alt text for when images do not load (many email clients block images by default). Use a descriptive alt text that conveys the message even without the image.
Rule 12: Use Button-Style CTAs
CTAs designed as buttons (with background color, padding, and borders) get 28% more clicks than text links. Use a contrasting color that stands out from your email design. Make buttons at least 44x44px (mobile tap target minimum). Use action-oriented text: "Get Your Free Guide" not "Click Here."
Automation Best Practices (Rules 13-15)
Rule 13: Set Up a Welcome Sequence Immediately
Welcome emails generate 320% more revenue than other promotional emails. A 5-7 email welcome sequence that delivers value, builds trust, and makes a soft pitch by email 5 converts 10-20% of new subscribers within 30 days. This is the single highest-ROI automation you can set up.
Rule 14: Always Set Exit Conditions on Automations
If a subscriber purchases during an abandoned cart flow, stop the flow. If they book a call during a nurture sequence, stop the sequence. Sending "buy now" emails to someone who already bought is embarrassing and damages trust. Every automation should have a clear exit condition based on the goal being achieved.
Rule 15: Segment Before Sending
Segmented campaigns generate 760% more revenue than generic blasts. Segment by purchase history, engagement level, location, or interests. Even basic segmentation (active vs inactive, buyers vs non-buyers) dramatically improves results. Use tags and custom fields to segment automatically based on subscriber behavior.
Deliverability Best Practices (Rules 16-18)
Rule 16: Authenticate Your Domain (SPF, DKIM, DMARC)
Email authentication tells ISPs that you are who you say you are. Without SPF, DKIM, and DMARC records, your emails are more likely to land in spam. Set up all three authentication protocols in your DNS records. Most email platforms provide step-by-step guides — GetResponse auto-generates the DNS records for you.
Rule 17: Clean Your List Quarterly
Remove subscribers who have not opened in 6+ months every quarter. A smaller, engaged list has better deliverability than a large, inactive one. ISPs track engagement — if you keep sending to inactive addresses, your deliverability drops and even engaged subscribers stop seeing your emails. Run a re-engagement campaign before removing inactive subscribers.
Rule 18: Warm Up New IP Addresses
If you switch to a dedicated IP, start by sending a small volume (500-1,000 emails/day) and gradually increase over 2-4 weeks. This builds sender reputation with ISPs. Sending 50,000 emails from a new IP on day one will trigger spam filters. Most platforms handle this automatically, but check your settings.
Compliance Best Practices (Rules 19-20)
Rule 19: Include a Visible Unsubscribe Link
CAN-SPAM, GDPR, and CASL all require a visible, working unsubscribe link in every email. Make it easy to find — do not hide it in tiny text or behind multiple clicks. If subscribers cannot find the unsubscribe link, they will hit "spam" instead, which hurts your deliverability far more than an unsubscribe does.
Rule 20: Include Your Physical Address
CAN-SPAM requires a valid physical postal address in every commercial email. Include it in the footer of every email. This can be a PO Box or registered business address. Non-compliance can result in fines up to $43,792 per email. Most email platforms automatically include this in the footer template.
Pro tip: GetResponse handles compliance automatically: unsubscribe links, physical address, and list management. It also includes domain authentication setup, A/B testing, and AI email builder — everything you need to follow all 20 best practices. Free plan for 500 contacts.
Best Tools for Following Best Practices
| Tool | A/B Testing | Domain Auth | Compliance | From |
|---|---|---|---|---|
| GetResponse | Yes | Auto | Auto | $19/mo |
| ActiveCampaign | Yes | Guide | Auto | $15/mo |
| MailerLite | Yes (free) | Guide | Auto | $10/mo |
| Klaviyo | Yes | Auto | Auto | $20/mo |
Follow All 20 Best Practices with One Tool
GetResponse handles A/B testing, domain authentication, compliance, automation, and AI email builder — everything you need to follow all 20 best practices.
Try GetResponse Free for 14 DaysFAQ
What is the most important email marketing best practice?+
If we had to pick one: set up automated email flows. Automated emails (welcome series, abandoned cart, post-purchase) generate 320% more revenue than manual campaigns. They run 24/7 without effort after setup. Start with a welcome sequence and abandoned cart flow — these two alone can transform your email revenue. Everything else is optimization on top of this foundation.
How do I avoid the spam folder?+
Follow these 5 rules: (1) Authenticate your domain with SPF, DKIM, and DMARC. (2) Clean your list quarterly — remove subscribers who have not opened in 6+ months. (3) Avoid spam trigger words in subject lines (FREE, GUARANTEE, ALL CAPS). (4) Keep image-to-text ratio at 40:60. (5) Include a visible unsubscribe link — if subscribers cannot unsubscribe, they will hit spam, which hurts your deliverability.
What email marketing laws do I need to comply with?+
Three major laws: (1) CAN-SPAM (US): requires unsubscribe link, physical address, and accurate subject lines. Fines up to $43,792 per email. (2) GDPR (EU): requires explicit consent before sending, easy opt-out, and data portability. Fines up to €20M or 4% of global revenue. (3) CASL (Canada): requires express or implied consent and identification of sender. Most email platforms handle compliance automatically — just make sure your settings are correct.
How often should I clean my email list?+
Clean your list quarterly. Remove subscribers who have not opened or clicked in 6+ months. Before removing them, run a re-engagement campaign: send 2-3 emails with your best content and a clear "Are you still interested?" message. Subscribers who do not respond to the re-engagement campaign should be removed. A smaller, engaged list has 30-50% better deliverability than a large, inactive one.