How does AT&T handle email filtering and infrastructure?

Key findings

• Hybrid infrastructure: AT&T email involves both AT&T's own mail transfer agents (MTAs) and Yahoo's (VMG) backend infrastructure for mail user agents (MUAs) and core filtering.
• Initial filtering: Email senders will encounter AT&T's proprietary filtering first, before messages are processed by the Yahoo/VMG backend.
• Deliverability tracking: Performance with AT&T email domains can sometimes follow a different pattern compared to other Yahoo/AOL/Verizon properties, despite shared backend infrastructure.
• Postmaster contact: For specific issues, it is crucial to consult bounce messages. If the error explicitly points to VMG, direct contact to their support may be necessary. For AT&T specific blocks or issues, you might need to contact the AT&T postmaster.

Key considerations

• Bounce message analysis: Always prioritize analyzing bounce codes and messages to accurately diagnose where an email delivery issue lies, whether with AT&T's initial checks or VMG's deeper filtering.
• Reputation monitoring: Closely monitor your sending reputation and blocklist (or blacklist) status specifically for AT&T domains, as their filtering can be distinct.
• Content and authentication: Ensure your emails adhere to best practices for content and authentication (SPF, DKIM, DMARC) to navigate both AT&T's and Yahoo's filtering systems effectively. For more, see AT&T Email Settings: A Guide for Email Marketers.

Key opinions

• Unique patterns: Many marketers find that AT&T email performance doesn't perfectly align with Yahoo, AOL, or Verizon, suggesting their own distinct filtering rules are heavily weighted.
• Aggressive filtering: Concerns have been raised about AT&T's spam filter being overly aggressive, potentially blocking legitimate emails without sufficient notification to the recipient.
• Bellsouth integration: Legacy Bellsouth.net email accounts now function as part of AT&T's email infrastructure, inheriting the same filtering mechanisms.
• Email-to-text sunset: AT&T has discontinued its email-to-text service due to security vulnerabilities, a move that impacts certain communication strategies. For alternatives, consider email-to-text services.

Key considerations

• User control: Marketers should be aware that AT&T Mail users have options to create custom filters for incoming emails, which can influence deliverability.
• Engagement metrics: Given the potential for aggressive filtering, maintaining strong email engagement with AT&T recipients is paramount to demonstrating sender legitimacy.
• Troubleshooting specific blocks: When facing issues specifically with AT&T domains, marketers should focus on troubleshooting that points to AT&T's systems rather than solely Yahoo's. More information can be found on what to do when AT&T blocks emails.

Key opinions

• Border vs. backend: AT&T manages the servers that receive initial email connections, but Yahoo (VMG) handles the deeper content and spam filtering.
• Filtering order: Emails are first subjected to AT&T's filtering mechanisms before being passed on to the Yahoo/VMG systems.
• Diagnostic importance: The specific error messages received during email bounces are critical for determining whether to address AT&T or VMG for resolution.
• PTR record issues: Some experts have noted that AT&T's servers sometimes fail to correctly process PTR records, even when they are properly configured on the sender's side, leading to deliverability problems. More information can be found on AT&T email issues.

Key considerations

• Layered troubleshooting: When troubleshooting AT&T deliverability, consider both AT&T's initial filtering and the downstream Yahoo/VMG systems, as either can be the source of blocks or delays.
• Authentication standards: Strong email authentication (SPF, DKIM, DMARC) is crucial, as misconfigurations can cause issues at both AT&T's border filters and Yahoo's backend. Refer to our simple guide to DMARC, SPF, and DKIM.
• Monitor blocklists: Keep a close eye on email blacklists (or blocklists), as listings can significantly impact delivery to AT&T and other ISPs.

Key findings

• User-configurable filters: AT&T provides users with the ability to create and manage their own email filters to sort incoming mail into folders, spam, or the inbox.
• Spam reporting: Documentation outlines steps for users to report unwanted email and adjust their spam filtering preferences directly through AT&T's support channels.
• Security initiatives: AT&T has announced collaborations, such as with Palo Alto Networks, to deliver secure access service edge (SASE) solutions for business customers, enhancing overall network security.
• Service discontinuations: The email-to-text service was officially shut down on June 17, 2025, due to its vulnerability as a 'spam magnet' and a source of 'smishing' attacks, as detailed in AT&T's support articles.

Key considerations

• Understanding user actions: Marketers should recognize that individual AT&T users have tools to directly influence email delivery to their inbox, through filtering rules and spam reporting.
• Policy updates: Stay informed about AT&T's official policy changes and service updates, especially those related to security or email gateway functions, as they can impact deliverability.
• Domain consolidation: Be aware that legacy domains such as Bellsouth.net are now part of the AT&T Mail ecosystem, meaning their filtering operates under the same combined rules. This is important when considering issues like block bounces.