Summary
AT&T's email filtering and infrastructure are a combination of in-house processes and outsourced services, primarily to Yahoo/VMG. While AT&T manages some aspects, like initial server connections and the Mail Transfer Agent (MTA) in some instances, a significant portion, including the Mail User Agent (MUA) and filtering for residential accounts and legacy domains (e.g., pacbell.net), is handled by Yahoo/VMG. AT&T also employs standard security measures such as SPF, DKIM, and DMARC and its network reputation is monitored by organizations like Spamhaus. Due to potentially aggressive spam filtering, legitimate emails may be blocked. Troubleshooting often involves checking spam folders and contacting AT&T or Yahoo support, depending on the domain and the specific issue. Peering agreements also affect deliverability.
Key findings
- Hybrid System: AT&T utilizes a hybrid email system with both in-house and outsourced components.
- Yahoo/VMG Partnership: Yahoo/VMG manages a substantial part of AT&T's email services, especially for residential users, including filtering, and for legacy domains.
- Aggressive Filtering: AT&T employs aggressive spam filtering, which may result in false positives.
- Standard Security: AT&T implements standard email security protocols, like SPF, DKIM, and DMARC.
- Network Monitoring: Organizations like Spamhaus monitor AT&T's network reputation.
- Peering Agreements: Peering agreements influence how email is routed and delivered.
Key considerations
- Check Spam: Always check the spam/junk folder if emails are missing.
- Contact Correct Support: Contact AT&T or Yahoo support depending on the domain and issue.
- Sender Compliance: Ensure senders follow email best practices to avoid filtering issues.
- Address Reputation: Maintain a good sending reputation to avoid being blocked.
- Whitelisting: If possible, whitelist important senders to prevent emails from being blocked.
What email marketers say
6 marketer opinions
AT&T's email infrastructure and filtering are handled through a combination of their own systems and partnerships with Yahoo (now VMG). While AT&T may have some border servers for initial filtering, the backend processes, particularly for residential accounts and legacy email addresses (like pacbell.net), are largely managed by Yahoo's infrastructure. This includes spam filtering, email processing, and storage. Due to potentially aggressive spam filtering, users may experience issues with legitimate emails being blocked. When issues arise, troubleshooting should begin with checking spam folders and potentially contacting AT&T or Yahoo support, depending on the specific domain and apparent source of the problem.
Key opinions
- Hybrid Infrastructure: AT&T uses a hybrid infrastructure for email, with some components handled in-house and others outsourced to Yahoo/VMG.
- Yahoo Partnership: A significant portion of AT&T's email services, especially for residential users, is managed by Yahoo's email infrastructure.
- Aggressive Spam Filtering: AT&T employs aggressive spam filtering, potentially leading to legitimate emails being blocked.
- Legacy Domains: Legacy AT&T domains (e.g., pacbell.net) are often managed separately through Yahoo Small Business.
Key considerations
- Check Spam Folders: If emails are missing, always check the spam/junk folders first.
- Contact Support: Contact AT&T or Yahoo support for assistance, depending on the email domain and the nature of the issue.
- Sender Best Practices: Advise senders to adhere to email best practices to improve deliverability to AT&T/Yahoo addresses.
- Whitelist Senders: If possible, whitelist important senders to prevent their emails from being blocked.
Marketer view
Email marketer from Reddit suggests in an older post from 2023 that AT&T uses aggressive spam filtering which can sometimes block legitimate emails. They recommend contacting AT&T support to whitelist specific senders if possible or advising senders to check their email sending practices align with best practices to improve deliverability.
25 Feb 2022 - Reddit
Marketer view
Email marketer from AT&T Community Forums explains that if you're having issues with receiving emails, particularly from specific senders, it might be due to AT&T's spam filters blocking those senders. They suggest checking the spam folder and adding the sender to your contacts list.
24 May 2023 - AT&T Community Forums
What the experts say
2 expert opinions
AT&T outsources significant portions of its email infrastructure, particularly the Mail User Agent (MUA) and associated filters, to Yahoo (now VMG). This means that while AT&T may handle the Mail Transfer Agent (MTA) functions, Yahoo/VMG is primarily responsible for filtering and other end-user email services.
Key opinions
- Email Services Outsourced: AT&T outsources key aspects of its email services to Yahoo/VMG.
- MUA/Filtering by Yahoo/VMG: Yahoo/VMG is responsible for the Mail User Agent (MUA) and email filtering for AT&T.
- MTA handled by AT&T: AT&T handles the Mail Transfer Agent (MTA) functions.
Key considerations
- Troubleshooting Focus: When troubleshooting email issues, consider Yahoo/VMG's infrastructure and filtering practices.
- Yahoo/VMG Policies: Email senders targeting AT&T users should be aware of Yahoo/VMG's email policies and best practices.
Expert view
Expert from Email Geeks explains that AT&T handles the MTA but outsources the MUA (and associated filters) to VMG.
13 Apr 2025 - Email Geeks
Expert view
Expert from Word to the Wise explains that AT&T outsources its email services to Yahoo, meaning Yahoo handles the mail transfer agent (MTA), including filtering, for AT&T's email service.
11 Mar 2025 - Word to the Wise
What the documentation says
3 technical articles
AT&T's email filtering and infrastructure involve peering agreements, network reputation monitoring, and standard email security measures. As a major ISP, AT&T engages in peering agreements affecting email routing and delivery. Spamhaus actively monitors AT&T's network reputation, implementing blocks for spam activity. AT&T utilizes SPF, DKIM, and DMARC to filter emails and actively block malicious content.
Key findings
- Peering Agreements: AT&T utilizes peering agreements to exchange email traffic with other networks, influencing deliverability.
- Network Reputation: Spamhaus monitors AT&T's network reputation, and AT&T blocks spam originating from its IP ranges.
- Email Security Features: AT&T employs standard anti-spam and anti-virus measures, including SPF, DKIM, and DMARC.
Key considerations
- Peering Impacts: Be aware that peering arrangements can affect email delivery speed and reliability.
- Spamhaus Compliance: Ensure email sending practices comply with Spamhaus policies to avoid blacklisting.
- Authentication Protocols: Implement SPF, DKIM, and DMARC to improve email deliverability to AT&T recipients.
Technical article
Documentation from Cisco explains that AT&T, as a major ISP, engages in peering agreements to exchange internet traffic, including email, with other networks. These peering arrangements directly affect how email is routed and delivered, potentially influencing deliverability based on network congestion and peering policies.
16 Dec 2022 - Cisco
Technical article
Documentation from AT&T details email security features which explains AT&T utilizes standard anti-spam and anti-virus measures, including SPF, DKIM, and DMARC, to filter incoming and outgoing emails. It also notes AT&T actively works to identify and block malicious content.
3 Oct 2023 - AT&T
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