Are hyphens or dashes allowed in email From names and subdomains?

Key findings

• Technical allowance: Hyphens are generally permitted within the local part of an email address (before the @ symbol) and in domain names or subdomains, adhering to specific rules regarding their placement.
• Subdomain validity: Dashes are acceptable in hostnames, including subdomains, as long as they are not at the beginning or end, or immediately adjacent to a dot or another dash.
• From name flexibility: In the 'From' name, hyphens are also usually fine, offering flexibility for branding, especially for company names that naturally include them. For more details on 'From' addresses, explore what the different terms for email From addresses are.
• Readability: Hyphens can improve the readability of long or compound names within an email address or subdomain, making them easier for recipients to process and recall.

Key considerations

• Cousin domains: Using hyphens to create cousin domains (domains slightly altered from a legitimate brand's domain, often by adding a hyphen) is highly discouraged. This practice is statistically associated with spam and phishing attempts, severely damaging sender reputation and deliverability. Learn about how multiple or external domains affect sender reputation.
• Trust and perception: Some sources suggest that domains without hyphens are perceived as more legitimate or trustworthy. While not a technical limitation, it can influence user experience and brand perception.
• Provider-specific rules: Although general technical standards permit hyphens, certain email service providers may have stricter internal policies or system limitations regarding their use in registered email addresses or domain names. For instance, some may not allow consecutive hyphens in subdomains.
• Deliverability impact: While hyphens themselves don't inherently cause deliverability issues, their use in suspicious patterns or in domains perceived as untrustworthy can lead to emails landing in spam or being blocked.

Key opinions

• Branding consistency: Many marketers find hyphens acceptable in 'From' names if they align with existing brand guidelines or company names that include dashes. This ensures recognition and trust among recipients.
• Readability enhancement: Hyphens are seen as a useful tool for breaking up long words or phrases within an email address, making it easier to read and remember for the user, which is crucial for email engagement.
• Common acceptance: While not universally preferred, hyphens are widely accepted by most email providers within the constraints of their allowed character sets, suggesting they don't inherently trigger rejections.
• Functional necessity: The primary concern is often ensuring that the email address, regardless of hyphens, points to a real, monitored mailbox for replies and deliverability feedback.

Key considerations

• Perception of trustworthiness: Some marketers and domain experts suggest that domain names without hyphens are perceived as more credible or professional. This perception, while subjective, can influence recipient trust and engagement.
• Potential for negative impact: Using hyphens in domain names can sometimes be seen as an indicator of a less reputable sender, potentially impacting email deliverability. This highlights the importance of overall sender reputation, which you can learn about in our guide to understanding your email domain reputation.
• Avoiding spam triggers: While not a direct cause, an unusual or overly complex email address with many hyphens might, in rare cases, contribute to an email being flagged by spam filters, particularly if other negative signals are present. To prevent this, focus on email deliverability issues.
• User experience: Even if technically valid, domains with hyphens can sometimes be harder for users to recall or type correctly, potentially leading to issues with subscriptions or direct outreach. This can impact overall user experience, as discussed by MNKY.agency.

Key opinions

• Strict hostname rules: Experts confirm that dashes are technically valid in hostnames (like subdomains), provided they adhere to specific placement rules, such as not being at the beginning or adjacent to dots or other dashes. More details on hostname and email address structure can be found by understanding what RFC 5322 says vs. what actually works.
• Local part flexibility: The part of the email address before the @ symbol (the local part) also allows hyphens, and their inclusion there is typically a sender's choice with full control.
• Subdomain preference: For sending emails on behalf of a client, experts strongly recommend using a properly delegated subdomain (e.g., email.client.com) rather than creating a cousin domain with hyphens. This is crucial for maintaining trust and deliverability, and is part of how ESPs manage domains, for example, for SPF records.
• Statistical association: Domains that appear similar to legitimate brands but include hyphens (or other minor alterations) are statistically linked to spammers and phishers, making them high-risk. This is a key area for those looking to find similar or misspelled email domains.

Key considerations

• Security enforcement evasion: Creating cousin domains with dashes to circumvent a client's security policies is a highly problematic practice that will negatively impact deliverability.
• Reputation risk: The perception that a domain owner using hyphens in such a manner is a spammer or phisher significantly increases the risk of emails being blocklisted or sent to the junk folder.
• Spam filter scrutiny: Even if technically valid, unusual domain or 'From' name structures with excessive hyphens can sometimes attract heightened scrutiny from spam filters, affecting inbox placement, as noted by SpamResource.
• User recall and trust: While hyphenated domains might be technically sound, an industry expert from Word to the Wise suggests they can be harder for users to remember or type correctly, impacting overall engagement and brand perception.

Key findings

• Domain name characters: Domain names are restricted to letters (A-Z), digits (0-9), and hyphens. Other symbols and spaces are explicitly not allowed in domain labels.
• Hyphen placement in domains: While hyphens are allowed in domain names (and subdomains), they cannot be used at the beginning or end of a domain label. Additionally, technical specifications like those for subdomains often state that consecutive hyphens are forbidden.
• Local part allowance: In the local part of an email address (the username before the @), hyphens are technically valid, often falling under a broader set of permissible characters defined by RFCs.
• Only spacing character: Hyphens are unique in being the only character that can act like a 'spacer' within a domain name, setting them apart from other punctuation marks. This is detailed by Fasthosts Blog.

Key considerations

• RFC compliance: Adhering to RFC standards for email addresses and domain names is fundamental for ensuring deliverability, as non-compliant formats may be rejected by mail servers. Understanding these standards is critical for robust email authentication setup.
• Specific prohibitions: Despite general allowance, documentation clearly prohibits hyphens at the start or end of a domain label and often discourages consecutive hyphens, which could lead to parsing errors or issues with DNS resolution.
• Evolution of standards: While RFCs provide core rules, interpretations and practical implementations by email service providers can vary, sometimes resulting in stricter interpretations or additional guidelines for character use, as indicated by Experian Data Quality Community.
• Distinction from other symbols: It's important to differentiate hyphens from other special characters like underscores or periods, which have different rules and implications for their use in email addresses and domain names.