Summary
To optimize email deliverability and engagement, avoid spam trigger words ('free,' 'urgent'), misleading subject lines, lack of personalization, excessive capitalization/punctuation, false promises, clickbait tactics, and URL shorteners. Adhere to email standards, avoiding specific characters that cause parsing issues. Use concise subject lines (around 50 characters), A/B test, use supported characters and preheader text. Proper authentication is key. Be wary of outdated advice like the pink background/AOL myth.
Key findings
- Spam Triggers: Spam trigger words and excessive punctuation negatively impact deliverability.
- Misleading Subjects: Misleading subject lines damage sender reputation and lead to unsubscribes.
- Character Issues: Certain characters and encoding issues can cause parsing problems.
- All Caps: All caps and excessive punctuation make emails look like spam.
- URL Shorteners: URL shorteners are viewed suspiciously by spam filters.
- Conciseness: Concise subject lines (around 50 characters) are best for mobile.
Key considerations
- Personalization: Personalize greetings to improve engagement.
- False Promises: Avoid false promises to maintain trust.
- Authentication: Ensure proper authentication to bypass spam filters.
- A/B Testing: A/B test subject lines for optimal open rates.
- Preheader Text: Utilize preheader text to supplement the subject line.
- Character Support: Use supported characters to ensure proper rendering.
- Outdated Advice: Be aware of outdated advice that is no longer valid.
What email marketers say
10 marketer opinions
Email subject lines should avoid spam trigger words, misleading content, lack of personalization, excessive capitalization/punctuation, false promises, and clickbait tactics. Concise subject lines (around 50 characters) are best for mobile readability. A/B testing, proper character usage, and utilizing preheader text are recommended for optimization.
Key opinions
- Spam Triggers: Using spam trigger words negatively impacts deliverability.
- Misleading Content: Misleading subject lines damage sender reputation.
- Excessive Caps/Punctuation: All caps and excessive punctuation can look like spam.
- Conciseness: Subject lines should be concise (around 50 characters).
Key considerations
- Personalization: Personalize greetings to increase engagement.
- False Promises: Avoid making false promises to maintain trust.
- A/B Testing: A/B test subject lines to optimize open rates.
- Preheader Text: Utilize preheader text to supplement the subject line.
- Character Usage: Use supported characters to ensure correct rendering.
Marketer view
Email marketer from Email on Acid explains that neglecting preheader text is a missed opportunity; use it to supplement the subject line.
21 Oct 2024 - Email on Acid
Marketer view
Email marketer from Email Marketing Forum explains that making false promises or exaggerating claims in subject lines can lead to distrust and unsubscribes.
14 Aug 2023 - Email Marketing Forum
What the experts say
6 expert opinions
Email subject lines should avoid spammy words like 'FREE' and excessive punctuation (!!!). Misleading subject lines are harmful. Using all caps can trigger spam filters. URL shorteners are suspicious. A/B testing is useful. Old advice about pink backgrounds and AOL blocking is no longer valid.
Key opinions
- Spam Words: Avoid using words like 'FREE' and excessive punctuation.
- Misleading Subjects: Misleading subject lines damage sender reputation.
- All Caps: Using all caps can trigger spam filters.
- URL Shorteners: URL shorteners in subject lines are suspicious.
Key considerations
- A/B Testing: A/B test subject lines to optimize results.
- Outdated Advice: Avoid outdated advice, such as the AOL pink background myth.
Expert view
Expert from Email Geeks shares that you shouldn’t use FREE or !!! in the subject line, based on something read on the internet.
25 Feb 2024 - Email Geeks
Expert view
Expert from Spam Resource shares that using all caps in subject lines is generally seen as shouting and can trigger spam filters.
30 Dec 2021 - Spam Resource
What the documentation says
3 technical articles
Email subject lines should adhere to email standards and avoid certain characters and formatting practices that could cause parsing or display issues. Avoiding spam triggers and ensuring proper authentication also helps improve deliverability.
Key findings
- Email Standards: Adhering to email standards improves deliverability.
- Character Issues: Certain characters and formatting can cause parsing problems.
- Spam Triggers: Avoiding spam triggers is essential for deliverability.
Key considerations
- Authentication: Ensure proper authentication to avoid spam filters.
Technical article
Documentation from Microsoft Documentation explains that adhering to email standards (like avoiding certain characters and encoding issues) is important for deliverability.
26 May 2022 - Microsoft Documentation
Technical article
Documentation from RFC Editor explains that certain characters and formatting practices should be avoided as they could cause issues with email parsing and display in some systems.
27 Feb 2023 - RFC Editor
Are spam trigger word lists accurate and should I be concerned about them?
Are spam trigger word lists still relevant for email deliverability?
Do all-emoji subject lines hurt email deliverability?
How does subject line length affect email deliverability and click-to-open rates on Yahoo and AOL?
Is it a good idea to put an email address in the subject line?
What words and phrases are considered spammy and trigger spam filters?
