Summary
High bounce rates for emails sent to AT&T, SBCGlobal, and Bellsouth domains have been a recurring concern for senders. These domains, often grouped due to historical mergers and shared infrastructure, exhibit unique and sometimes aggressive spam filtering behaviors. Senders frequently report receiving 100% bounces, indicating widespread delivery issues that can affect both transactional and promotional email campaigns. The problem often stems from AT&T's specific filtering policies and its use of internal or public blocklists (blacklists) that can flag entire IP ranges, even for legitimate senders.
Key findings
- Widespread Bounces: Many senders have reported experiencing high bounce rates, including 100% bounces, specifically for AT&T, SBCGlobal, and Bellsouth email addresses.
- Legitimate Email Filtering: Even valid user emails and necessary communications, such as transactional messages, are being marked as spam or blocked by these domains.
- IP Range Blocklisting: In severe cases, entire Class C IP ranges used by senders have been blocklisted, resulting in delivery failures for all emails originating from those IPs.
- DNSBL:RBL Bounce Codes: Bounces often include the DNSBL:RBL message, indicating that the sending IP is listed on a DNS-based blocklist (also known as a blacklist).
- No Cloudmark Usage: AT&T's email systems (including SBC and Bellsouth) do not primarily rely on Cloudmark for their filtering, implying they use their own proprietary or distinct spam prevention mechanisms.
Key considerations
- Monitor Complaints: Regularly checking your complaint rates and feedback loops is crucial, as valid emails might be flagged as spam by recipients, contributing to negative sender reputation. This can help you diagnose a sudden spike in email bounce rates more effectively.
- Check Blocklists: If you are encountering block bounces, particularly with DNSBL:RBL messages, it is essential to check your IP and domain against various blocklists.
- Authentication Standards: Ensure your email authentication records (SPF, DKIM, DMARC) are correctly configured and aligned to build and maintain a strong sender reputation, which is crucial for bypassing strict filters.
- Content and Engagement: Beyond technical settings, review your email content for potential spam triggers and focus on sending engaging, valuable emails to an active list to improve overall deliverability and reduce complaints.
What email marketers say
Email marketers widely report significant and persistent deliverability challenges with AT&T, SBCGlobal, and Bellsouth email domains. These issues range from complete blocks to legitimate emails landing in spam folders, impacting both critical transactional messages and marketing campaigns. The common thread among their experiences points to an aggressive, and sometimes opaque, filtering system employed by AT&T that can indiscriminately affect senders, even those with good practices. This consensus highlights the need for constant vigilance and adaptive strategies when targeting these particular domains.
Key opinions
- Universal Impact: Many marketers confirm seeing widespread issues with AT&T, SBCGlobal, and Bellsouth, extending beyond occasional bounces to consistent blockages.
- Bot Submission Concerns: Some report experiencing high volumes of bot submissions originating from sbcglobal addresses, potentially skewing metrics or triggering filters.
- Spam Folder Misclassification: Valid subscriber emails are frequently being incorrectly routed to spam or junk folders, severely impacting engagement and visibility.
- Broad Impact on Campaigns: Both essential transactional emails and broader promotional campaigns are equally affected by these deliverability challenges, highlighting a fundamental issue with AT&T's filtering.
- DNSBL Blockage: Marketers frequently observe DNSBL:RBL bounce messages, indicating their IPs are listed on blocklists used by AT&T.
Key considerations
- Proactive Monitoring: It is essential for marketers to continuously monitor their bounce rates and sender reputation specifically for AT&T, SBCGlobal, and Bellsouth domains, as issues can arise suddenly.
- Complaint Management: Prioritize rapid identification and resolution of complaints to prevent further damage to sender reputation with AT&T, which is known to be sensitive to user feedback.
- Understand AT&T's Filters: Acknowledge that AT&T employs its own filtering mechanisms (not Cloudmark), which may require unique strategies compared to other ISPs. For instance, sometimes data limiting can occur.
- Segment Campaigns: Consider segmenting email lists to identify AT&T, SBCGlobal, and Bellsouth recipients and tailor sending practices or content specifically for them if issues persist.
Marketer view
Marketer from Email Geeks notes seeing widespread issues beyond 100% bounce, including bot submissions from SBCGlobal impacting new clients. They highlight that this points to a broader problem affecting overall deliverability for those domains.
Marketer view
Email marketer from Email Geeks observes that some senders are indeed experiencing the same problem, indicating a shared challenge within the email community. This commonality suggests the issue is not isolated to a single sender's practices.
What the experts say
Email deliverability experts often point to AT&T's distinct and sometimes aggressive filtering policies as the root cause of high bounce rates for domains like SBCGlobal and Bellsouth. They suggest that AT&T operates independently, not always aligning with industry-standard spam prevention methods, leading to unique challenges for senders. These experts emphasize the critical role of strong sender reputation, proper email authentication, and continuous monitoring of blocklist (blacklist) statuses to navigate AT&T's complex filtering landscape and improve inbox placement.
Key opinions
- Aggressive Filtering: Experts commonly attribute high bounce rates to AT&T's highly aggressive spam filtering mechanisms, which can inadvertently impact legitimate emails.
- Reputation Shifts: Unexpected spikes in bounce rates from ISPs like AT&T often indicate a sudden shift in sender reputation or a system-wide filter adjustment on their end.
- DNSBL Listings: If entire IP ranges are experiencing bounces, it's crucial to check for DNSBL (Domain Name System Blocklist) listings, as these are frequently used by AT&T.
- PTR Record Misinterpretation: AT&T's infrastructure may struggle with correctly interpreting certain email authentication records, such as PTR records, even if they are properly configured by senders.
- Spam Wave Correlation: Large-scale blocks by ISPs like AT&T often correlate with detected spam waves or unusual sending patterns, leading to collateral damage for legitimate senders.
Key considerations
- Maintain Clean Lists: Actively managing your mailing list to remove inactive or bouncing addresses is paramount. This helps improve your overall domain reputation with strict ISPs like AT&T.
- Proactive Postmaster Engagement: If persistent bounce issues arise, proactively engaging with AT&T's postmaster resources is recommended, as general deliverability best practices alone might not suffice for their unique filtering.
- Authentication Compliance: Ensuring robust email authentication (SPF, DKIM, DMARC) is vital, as it builds trust and helps bypass stringent filters. For more details, refer to our simple guide to DMARC, SPF, and DKIM.
- Monitor External Blocklists: Regularly check major public blocklists (blacklists) to ensure your sending IPs and domains are not listed, as AT&T uses various RBLs.
Expert view
Email deliverability expert from SpamResource cautions that AT&T (and its associated domains like Bellsouth and SBCGlobal) often employs highly aggressive spam filtering mechanisms that can impact legitimate mail. They stress the importance of understanding these unique filters.
Expert view
An expert at Word to the Wise notes that unexpected high bounce rates from major ISPs like AT&T can signal a sudden reputation shift or a system-wide filter adjustment on their end. They recommend vigilance for such changes.
What the documentation says
Technical documentation and analyses shed light on the specific operational challenges that contribute to email deliverability issues with AT&T, SBCGlobal, and Bellsouth domains. These sources often detail how AT&T's internal systems process email, highlighting potential quirks such as difficulties in resolving correctly configured PTR records or the aggressive application of spam filters in response to perceived threats. Understanding these technical underpinnings is crucial for senders aiming to optimize their email infrastructure and content for successful delivery to these challenging recipient domains.
Key findings
- PTR Record Resolution Issues: Despite correct PTR record configuration by senders, AT&T's servers may fail to properly interpret or resolve them, leading to delivery failures.
- Aggressive Spam Filter Updates: AT&T has implemented upgraded spam filters that have, at times, become overly aggressive, unintentionally catching a significant volume of legitimate emails.
- Spam Wave Blocking: AT&T's servers are known to block connections from major email service providers (like Microsoft 365) in response to detected high-volume spam waves, causing delays or blocks.
- Data Limiting Policies: Some domains (including AT&T related ones) may use internal data limiting to control the volume of emails accepted from a single sender, impacting large-scale campaigns.
Key considerations
- Verify DNS Records: Double-check the validity and correct configuration of all DNS records, especially PTR records, even if they appear correct to standard checkers. This is vital to avoid issues like hidden SPF DNS timeouts.
- Understand ISP-Specific Quirks: Recognize that AT&T's filtering system may have unique quirks compared to other ISPs. General email deliverability issues require tailored solutions for these domains.
- Adapt Sending Practices: Be prepared to adjust sending volumes, frequencies, and content in response to AT&T's filtering behavior, especially during periods of observed spam waves affecting major senders.
- Regular Blacklist Checks: Even with perfect practices, being caught in a broader block is possible. Regularly checking your IPs on DNSBLs (blacklists) and requesting delisting when appropriate is important.
Technical article
AT&T Email Customer Support documentation advises checking for blocked addresses within your account and ensuring emails are not being diverted by personal filters configured within the recipient's mailbox. They highlight the importance of basic mailbox hygiene for recipients.
Technical article
Network Solutions, Inc. highlights that Microsoft's servers possess correct PTR records, but AT&T's servers sometimes fail to resolve them correctly, leading to delivery issues. This suggests a potential interoperability challenge between systems.
Related resources
8 resources
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