How does AT&T handle email filtering and infrastructure?

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.

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.

Email marketer from DSLReports explains that if you are using an old Pacbell.net email address (legacy AT&T) then this is actually managed by Yahoo Small Business. If you are having issues with deliverability then you should follow the Yahoo support paths to resolve

Email marketer from EmailProviderReviews.com shares that AT&T partners with Yahoo for residential email services, which means Yahoo's infrastructure handles much of the email processing, storage, and filtering for AT&T email addresses.

Marketer from Email Geeks explains that AT&T uses its own servers at the border but the backend is Yahoo (now VMG), meaning you'll hit AT&T's own filtering first and to follow what you're seeing in the errors.

Email marketer from DNSQueries shares that AT&T's email setup uses MX records that point to Yahoo's servers, which indicates that Yahoo handles their mail exchange. This confirms that AT&T leverages Yahoo's email infrastructure for email routing.

Expert from Email Geeks explains that AT&T handles the MTA but outsources the MUA (and associated filters) to VMG.

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.

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.

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.

Documentation from Spamhaus explains that AT&T's network reputation is actively monitored, and blocks are implemented based on spam activities originating from its IP ranges. Senders need to ensure their practices comply with Spamhaus's policies to avoid being blacklisted by AT&T and other networks.