Summary
MX records (Mail Exchanger records) are a crucial type of DNS record that specifies which mail servers are responsible for accepting email messages on behalf of a domain. While technically a domain can receive mail via an A record if no MX record is present, the absence of an MX record on a sending domain, particularly the "from" domain, can negatively affect email deliverability. Mail servers often perform checks for MX records as a fundamental part of their validation process.
Key findings
- Purpose: MX records are essential for directing incoming emails to the correct mail server for a given domain.
- Deliverability impact: The absence of an MX record on the 'from' domain can signal a misconfigured or suspicious sender, leading to emails being rejected, sent to spam, or otherwise failing to deliver.
- Standard practice: Having a properly configured MX record is considered a standard best practice for any domain that sends email, regardless of whether it expects to receive direct replies.
- Sender reputation: A missing MX record can negatively impact your sender's reputation, potentially leading to future email blocklisting or blacklisting.
Key considerations
- Accept mail: Even if you use a "no-reply" address, the domain should still be configured to accept mail, even if those emails are ultimately discarded or auto-replied. For more, see our page on sending email from a domain without an MX record.
- Scanning tools: Many receiving mail transfer agents (MTAs) and spam filters perform checks specifically for the presence of an MX record on the sending domain. If it's missing, they may immediately flag the email, impacting your sender reputation.
- Ease of check: Checking for an MX record is often an easier and less intrusive method for mail servers to validate a sender compared to attempting a full SMTP connection (pingback) to port 25.
- RFC compliance: While RFC 5321 (SMTP) states that if no MX record exists, an A record can be used as a fallback, modern email systems often expect an MX record for routine validation and trust. A blog post by Service Objects highlights that MX records are essential for email deliverability.
What email marketers say
Email marketers often focus on practical implications for campaign performance and inbox placement. While they might not delve into the deepest technical specifications, they recognize that foundational DNS settings like MX records are critical for ensuring emails reach their audience. For marketers, the core concern is avoiding spam folders and maximizing engagement, which proper domain configuration directly supports.
Key opinions
- Essential for delivery: Marketers widely agree that MX records are essential for email deliverability, as they ensure mail servers know where to send replies.
- Impact on trust: Sending from a domain that lacks an MX record can make emails appear untrustworthy to receiving mail systems.
- "No-reply" addresses: While the primary focus is MX records, some marketers find "no-reply" addresses off-putting and detrimental to user experience.
- Avoid deliverability issues: Proper MX record setup is a fundamental step to prevent emails from being blocked or directed to spam.
Key considerations
- Recipient trust: A properly configured domain, including MX records, helps build trust with recipients and mailbox providers. This plays a role in how different domains affect deliverability.
- Automation focus: When using "no-reply" addresses, ensure the underlying domain is still configured correctly, even if replies are automated or discarded.
- Consistency: Maintaining consistent domain configurations for both sending and potential reply paths is important for inbox placement and avoiding the spam folder. Check out our guide on why your emails are going to spam.
- Basic hygiene: Setting up MX records is seen as a basic requirement for email hygiene and a prerequisite for successful email marketing, as noted in a Mailmunch article on email deliverability best practices.
Marketer view
Marketer from Email Geeks observes that a subdomain, such as alerts.domain.com, currently lacks an MX record and queries if this impacts deliverability, especially when the main domain does have one. They also raise questions about the effect of using a reply-to address on the same sending subdomain.
Marketer view
Email marketing expert from Mailmodo emphasizes that having an MX record is essential to improve email delivery reliability and ensure consistent communication. They note that updating MX records can significantly enhance email delivery.
What the experts say
For email experts, the presence of an MX record on a sending domain isn't just a recommendation, it's a fundamental expectation for proper email ecosystem behavior. They view the absence of such a record, especially on the 'from' domain, as a strong indicator of poor configuration or even potentially malicious intent, which can significantly hinder deliverability.
Key opinions
- Mail acceptance is crucial: Experts strongly believe that both the Mail From (5321) and From (5322) domains should be configured to accept mail, regardless of whether replies are actively managed.
- Bad practice: Sending from a domain that does not accept mail (or has no MX record to facilitate acceptance) is considered "anti-social behavior" in the email world.
- Scanning expectations: Many mail scanning tools and filters will check specifically for the existence of an MX record and may not proceed to look for A records as a fallback.
- Deliverability impact: While direct proof can be elusive, experts widely agree that lacking an MX record will negatively impact deliverability and can be a "negative tick mark" in filtering systems.
Key considerations
- Easier validation: Checking for an MX record is a simpler and less intrusive way for receiving servers to validate a sender compared to attempting a connection to port 25. For more on how domain reputation is built, see our guide to understanding email domain reputation.
- Don't overcomplicate: Setting up an MX record, even if it points to a server that discards mail, is a minimal effort that can prevent significant deliverability issues. This is also covered in SocketLabs' blog on improving email deliverability.
- Perception of trust: A domain that is not set up to receive mail can appear less legitimate or less invested in good email practices, affecting how the 5322.from domain affects delivery.
- Industry standard: Although RFCs might allow A records as a fallback, the de facto industry standard expects a proper MX record for reliable mail flow.
Expert view
Expert from Email Geeks recommends that both the 5321 (Mail From) and 5322 (From) domains should be configured to accept mail. This dual configuration is crucial for proper email communication.
Expert view
Email deliverability consultant from Spam Resource often discusses the importance of proper DNS records for sender authentication and avoiding spam filters. They emphasize that correct configuration is a cornerstone of good deliverability.
What the documentation says
Official documentation and technical specifications for email protocols, such as RFCs, outline the fundamental requirements for mail exchange. While RFCs provide the baseline, the practical implementation by modern mail service providers often imposes stricter expectations, making the presence of an MX record on sending domains a de facto requirement for reliable deliverability.
Key findings
- RFC 5321 (SMTP): Specifies that if no MX record is found for a domain, a mail transfer agent (MTA) should attempt to deliver mail using the domain's A (or AAAA) record.
- Sender verification: While not explicitly a "deliverability" factor in RFCs, the ability of a sender domain to accept mail (indicated by MX records) is a common check performed by receiving MTAs for legitimacy.
- Error handling: The absence of a valid MX record can lead to soft failures or delays as receiving servers try to resolve the domain using fallback mechanisms, if at all.
- Best practice vs. requirement: While the RFCs allow for an A record fallback, most modern mail systems treat a proper MX record as a strong indicator of a legitimate, well-configured sender.
Key considerations
- Modern implementations: Relying solely on A records for mail acceptance is technically permissible but is often not sufficient for good deliverability in today's email ecosystem. Understand the fundamentals with our guide to DMARC, SPF, and DKIM.
- Spam filtering: Many spam filters and blocklists use the presence or absence of standard DNS records, including MX, as a scoring factor for incoming mail. Learn how email blacklists work.
- Bidirectional communication: A domain that sends email should ideally be capable of receiving email, even if only for bounce management or feedback loops.
- Domain reputation: Proper DNS configuration, including MX records, contributes positively to a domain's overall reputation with mailbox providers. The Webex Connect documentation also advises on best practices for deliverability.
Technical article
Documentation from Abnormal AI's glossary explains that MX records are a standard part of email delivery infrastructure, essential for a domain to receive emails. This highlights their fundamental role in inbound email.
Technical article
Platform documentation from Webex Connect recommends businesses set up a valid reverse DNS record to ensure the IP address they are sending emails from points back to their domain, enhancing email deliverability. This comprehensive approach to DNS is key.
Related resources
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Related pages
Is it bad practice to send email from a domain without an MX record?
How do MX records impact email bounces and sender reputation?
Should the 5322.from domain identically match the d= domain for optimum email delivery?
Does using different domains in From and Reply-To email addresses affect deliverability?
Does sending email from a domain without a website hurt deliverability?
A simple guide to DMARC, SPF, and DKIM
A practical guide to understanding your email domain reputation
Why Your Emails Are Going to Spam in 2024 and How to Fix It
Boost Email Deliverability Rates: Technical Solutions from Top Performing Senders
What happens when your domain is on an email blacklist?
