Summary
The overwhelming consensus from email marketers, deliverability experts, and official documentation is that using the letter 'O' instead of the number '0' in email subject lines is a detrimental practice. Character substitutions can trigger spam filters, harm sender reputation, decrease user trust, reduce accessibility, and make emails appear unprofessional. While some suggest A/B testing, the potential risks generally outweigh any perceived benefits. Clarity, authenticity, and adherence to email marketing best practices are emphasized as key for successful and ethical email communication.
Key findings
- Spam Trigger: Character substitutions are easily detected by spam filters, leading to decreased deliverability.
- Reputation Damage: Such practices negatively impact sender reputation, potentially causing emails to be marked as spam.
- Reduced Trust: Using 'O' instead of '0' is seen as a deceptive tactic, reducing user trust and credibility.
- Accessibility Issues: Character substitutions can make emails less accessible and readable for all users.
- Unprofessional Appearance: Emails with these substitutions are perceived as unprofessional and potentially suspicious.
Key considerations
- Authenticity and Transparency: Prioritize genuine and transparent communication over stylistic tricks.
- Policy Compliance: Adhere to the anti-spam policies of major email providers like Google and Microsoft.
- Sender Reputation Management: Actively monitor and maintain a positive sender reputation to ensure optimal deliverability.
- A/B Testing (Cautiously): If considering this practice, carefully A/B test the impact on deliverability and engagement, but be wary of potential negative consequences.
What email marketers say
11 marketer opinions
The consensus among email marketers and experts is that using the letter 'O' instead of the number '0' in email subject lines is generally a bad practice. This is due to concerns about accessibility, deliverability, and professionalism. While some suggest A/B testing, most agree the risks outweigh any potential benefits, as such substitutions can trigger spam filters, reduce readability, annoy subscribers, and harm sender reputation. Clear and genuine communication is prioritized over potentially deceptive character replacements.
Key opinions
- Deliverability Impact: Character substitutions can trigger spam filters and negatively affect sender reputation.
- Accessibility Concerns: Using 'O' instead of '0' can reduce readability and negatively impact accessibility for some users.
- Professionalism: The practice makes emails look unprofessional and potentially deceptive.
- Lack of Proven Benefits: There is no evidence to suggest that using 'O' instead of '0' improves email performance.
Key considerations
- A/B Testing: While generally discouraged, A/B testing can be used to assess the specific impact on deliverability and engagement.
- Target Audience: Consider whether the target audience might perceive the substitution as creative or confusing.
- Brand Image: Evaluate whether the substitution aligns with the brand's overall image and communication style.
- Accessibility: Ensure email design and practices adhere to accessibility standards for all users.
Marketer view
Email marketer from MarketingProfs advises against using letter substitutions in subject lines. They suggest that while creativity is important, clarity and professionalism should take precedence to maintain credibility.
9 Sep 2022 - MarketingProfs
Marketer view
Marketer from Email Geeks suggests testing the approach and notes that organizations sometimes follow outdated practices without proven benefits.
29 Oct 2022 - Email Geeks
What the experts say
1 expert opinions
Laura Atkins, an expert from Word to the Wise, advises against using character substitutions like 'O' instead of '0' in email subject lines. She emphasizes that such practices make emails look unprofessional, trigger spam filters, and harm sender reputation because they often signal an attempt to deceive sophisticated email filters.
Key opinions
- Negative Perception: Character substitutions make emails look unprofessional.
- Spam Trigger: Such substitutions can trigger spam filters.
- Reputation Harm: The practice damages sender reputation by suggesting deceptive intent.
Key considerations
- Professionalism: Maintain a professional appearance in email communications.
- Deliverability: Avoid practices that could negatively impact email deliverability.
- Sender Reputation: Protect sender reputation by avoiding deceptive or questionable tactics.
Expert view
Expert from Word to the Wise, Laura Atkins, explains that character substitutions like using 'O' instead of '0' are a bad idea because they make an email look unprofessional and trigger spam filters. She notes that while email filters are becoming more sophisticated, these kinds of substitutions are often a sign that the sender is trying to hide something, therefore harming sender reputation.
9 Mar 2022 - Word to the Wise
What the documentation says
4 technical articles
Email deliverability documentation from Spamhaus, Google Support, Microsoft Support, and Mailchimp Resources all advise against using character replacements, such as 'O' instead of '0', in email subject lines. They emphasize that modern spam filters detect these tactics, which can negatively affect sender reputation, user trust, and deliverability, potentially leading to emails being marked as junk. Authenticity and clear communication are key for successful email marketing.
Key findings
- Spam Detection: Modern spam filters are capable of detecting character replacements.
- Negative Reputation Impact: Character replacements can negatively affect sender reputation.
- Reduced Trust: Using such tactics reduces user trust.
- Policy Violations: These practices violate anti-spam policies of major email providers.
Key considerations
- Authenticity: Prioritize authentic and genuine communication.
- Clear Communication: Focus on clear and straightforward messaging.
- Policy Compliance: Adhere to anti-spam policies of email providers.
- Reputation Management: Actively manage and protect sender reputation.
Technical article
Documentation from Google Support emphasizes the importance of clear and genuine communication. Using character replacements can be seen as deceptive, impacting user trust and deliverability to Gmail accounts.
17 Jun 2023 - Google Support
Technical article
Documentation from Microsoft Support warns against using deceptive techniques, including character substitutions. These practices violate their anti-spam policies and can result in emails being marked as junk.
11 Feb 2023 - Microsoft Support
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