Who is responsible for setting up my PTR record?

Reverse DNS (PTR) records are managed by the ISP or hosting provider that owns the IP address block. You need to contact them directly to request the creation or modification of your PTR record, as you typically cannot do this yourself through your domain registrar.

Why is a PTR record important for email deliverability?

A PTR record maps an IP address to a domain name. For email, it's crucial because recipient servers like AT&T's perform a reverse lookup to verify that the connecting IP address belongs to the domain it claims to be from. If this lookup fails, it raises suspicion and can lead to email rejection (or being placed on a blacklist).

How can I check and fix my reverse DNS?

First, use a tool like dig -x [your IP] or an online reverse DNS checker. If the PTR record is missing or incorrect, contact your ISP or hosting provider immediately. Also, ensure your email server's HELO/EHLO greeting matches the PTR record to avoid SMTP banner mismatches.

How long does it take for PTR record changes to propagate?

It can take anywhere from a few hours to 48 hours for DNS changes, including PTR records, to fully propagate across the internet. During this time, you might still experience intermittent failures, but they should resolve as the new record becomes widely recognized.

What causes reverse DNS failures from AT&T and how can they be resolved? - Troubleshooting - Email deliverability - Knowledge base

Email deliverability can be a complex landscape, and few things are as frustrating as encountering unexpected bounce messages. One common hurdle, especially for senders reaching users on AT&T, SBCGlobal, and Bellsouth domains, is reverse DNS failure. This issue means your email server's IP address isn't properly identifying itself, leading to rejections. It's a critical component of email authentication, and when it fails, recipients' servers, particularly AT&T's, often block (or blacklist) your messages outright.

These failures are not just minor glitches, they directly impact your email campaigns and communication. If AT&T's mail servers can't perform a full circle reverse DNS check on your sending IP address, they will likely return a bounce message indicating that the connection was not accepted. This guide will explore the common causes behind these frustrating reverse DNS failures and provide actionable steps to resolve them, ensuring your emails reach their intended recipients.

Understanding why AT&T is bouncing emails due to reverse DNS issues is the first step toward a smoother email flow. It's often a technical oversight or a temporary network hiccup, but either way, it requires attention to maintain healthy email deliverability.

Understanding reverse DNS and AT&T's requirements

Reverse DNS, also known as a Pointer (PTR) record, is essentially the opposite of a standard DNS A record. While an A record translates a domain name into an IP address, a PTR record translates an IP address back into a domain name. This lookup is crucial for email servers to verify the legitimacy of incoming connections.

AT&T, like many other major mailbox providers, places significant emphasis on properly configured reverse DNS. If an email server connects to AT&T's network, AT&T will perform a reverse DNS lookup on the connecting IP. If this lookup fails, or if the PTR record doesn't align with the sending domain, AT&T's servers are likely to reject the email with a bounce message such as "550 5.7.1 Connections not accepted from servers without a valid sender domain."

It's important to understand that PTR records are managed by the Internet Service Provider (ISP) or hosting provider that owns the IP address block. Unlike other DNS records that you typically manage within your domain registrar or DNS host, PTR records require you to contact your ISP to set them up or request changes. This is often a source of confusion and a common reason for reverse DNS failures, especially when senders are unaware of this delegation.

You can quickly check your reverse DNS using command-line tools like dig or nslookup by querying the IP address with the -x option, or through various online reverse DNS lookup tools. This initial check is crucial for pinpointing whether the issue lies with your setup or elsewhere.

Common causes of AT&T reverse DNS failures

Reverse DNS failures from AT&T (and its associated domains like sbcglobal.net or bellsouth.net) primarily stem from two categories: misconfigurations on the sender's side (or their ISP's) and, less frequently, temporary issues within AT&T's own network infrastructure. Identifying the root cause is essential for effective troubleshooting.

Common misconfigurations

Missing PTR record: Your sending IP address does not have an associated PTR record defined by your ISP or hosting provider.
Mismatching PTR record: The PTR record exists, but it points to a different domain name than the one specified in your email server's HELO/EHLO greeting. This SMTP banner mismatch is a red flag for spam filters.
Incorrect delegation: If you manage your own DNS, your ISP might not have correctly delegated the reverse DNS zone to your name servers, preventing proper lookups.

Beyond misconfigurations, occasional temporary DNS resolution issues can occur on AT&T's side. This means your PTR record might be perfectly valid, but AT&T's mail servers (or specific data centers) are temporarily unable to resolve it. In such cases, the bounce message might still point to a reverse DNS issue, even though the problem lies with the recipient's DNS infrastructure rather than yours. These are often transient and resolve on their own, but can cause significant disruption.

The combination of strict reverse DNS requirements and occasional internal DNS hiccups makes AT&T a particularly challenging recipient for email senders. Understanding these nuances is key to effectively troubleshooting and resolving deliverability challenges.

Diagnosing and resolving AT&T reverse DNS issues

Addressing reverse DNS failures with AT&T involves a systematic approach, starting with verification and moving to communication with your service providers. Here's how to diagnose and resolve these issues:

Check your PTR record: Use a command-line tool like dig -x [your IP address] or an online blocklist checker (which often include PTR checks) to verify that your IP address resolves to the correct domain name. This is the first and most critical step. If you find your PTR record is incorrect or missing, you've likely found your problem.
Contact your ISP/hosting provider: Since they control the IP address space, your ISP or hosting provider is responsible for setting up and modifying PTR records. Provide them with your sending IP address and the exact domain name you want it to resolve to. Clearly state that this is for email deliverability and is required by mailbox providers like AT&T.
Verify SMTP banner: Ensure your email server's HELO/EHLO greeting matches the domain name specified in your PTR record. A mismatch can also trigger rejections, even if the PTR record is otherwise valid.

Sometimes, the issue isn't with your configuration but a temporary problem on AT&T's side. If your PTR record is correctly configured and resolving globally, but you're still seeing bounces from AT&T, it might indicate a transient DNS resolution issue within their network. In such cases, monitoring the situation and waiting for a resolution from AT&T is often the only course of action.

Checking your reverse DNS

Example: Using dig to check PTR recordbash

$ dig -x 203.0.113.45 +short
mail.yourdomain.com.

Resolution timeline

Once your ISP or hosting provider implements the PTR record, it can take some time for the changes to propagate across the internet's DNS system. This usually takes a few hours, but in some cases, it might take up to 48 hours to fully update. Continue to monitor your bounce rates and check your reverse DNS periodically.

Preventing future reverse DNS problems

Preventing reverse DNS issues from affecting your email deliverability, especially with gatekeepers like AT&T, requires ongoing vigilance and adherence to email best practices. It's not just about fixing a problem, but building a resilient email infrastructure.

Regular monitoring: Regularly check your PTR records and other DNS records to ensure they remain correct and consistent. Automated monitoring tools can alert you to changes or failures.
Maintain sender reputation: Beyond technical configurations, your sender reputation plays a massive role. Avoid spam complaints, keep your lists clean, and send engaging content. A poor reputation can lead to being added to a blacklist (or blocklist), making reverse DNS even more critical.
Implement email authentication: Ensure you have properly configured SPF, DKIM, and DMARC records. These authentication protocols provide additional layers of trust that can help your emails get delivered even if a minor issue like a temporary reverse DNS lookup failure occurs.
Choose a reliable ESP: If you use an Email Service Provider (ESP), they should manage reverse DNS for their shared or dedicated IP addresses. Choose a provider with a strong focus on deliverability and proper infrastructure management.

Proactive management of your email sending infrastructure, including technical configurations like reverse DNS, is paramount for consistent email deliverability, especially when dealing with major ISPs. By taking these steps, you can significantly reduce the likelihood of encountering reverse DNS failures from AT&T and other providers.

Views from the trenches

Best practices

Always ensure your sending IP has a valid PTR record that matches your HELO/EHLO greeting.

Regularly monitor your email logs for DNS-related bounce messages to catch issues early.

Maintain open communication with your ISP or hosting provider regarding PTR record management.

Implement a comprehensive suite of email authentication protocols: SPF, DKIM, and DMARC.

Common pitfalls

Assuming your PTR record is automatically set up correctly by your ISP or hosting provider.

Neglecting to align your SMTP banner with your PTR record, leading to soft bounces or rejections.

Not having a clear point of contact at your ISP for reverse DNS requests and issues.

Overlooking temporary AT&T network issues, attributing all failures to your own configuration.

Expert tips

Use automated monitoring to track your IP's PTR status, as manual checks can be prone to oversight.

When encountering AT&T issues, check community forums for widespread outages before extensive troubleshooting.

Prioritize sending IP addresses that demonstrate better DNS resolution performance within AT&T's network.

Document all communications with your ISP regarding PTR record setup and changes for future reference.

Marketer view

Marketer from Email Geeks says they were also experiencing AT&T reverse DNS failures.

2025-02-17 - Email Geeks

Expert view

Expert from Email Geeks says many people have reported the issue, confirming it is widespread.

2025-02-17 - Email Geeks

Summary and next steps

Reverse DNS failures from AT&T can be a significant roadblock to email deliverability, often leading to rejected messages and frustrating bounce backs. These issues typically stem from either a missing or misconfigured PTR record for your sending IP address, or occasionally from transient DNS resolution problems within AT&T's network itself.

The key to resolution lies in verifying your PTR record, ensuring it correctly maps your IP to your sending domain, and then liaising with your ISP or hosting provider to rectify any discrepancies. Coupled with vigilant monitoring and robust email authentication practices like SPF, DKIM, and DMARC, you can minimize the impact of these failures and maintain a healthy email sending reputation. Consistent effort in these areas will ensure your messages reliably reach AT&T inboxes.