Why are email clients being blocked by AT&T and how was it resolved?

AT&T's email blocking issues stem from a combination of factors, including a major outage, stricter filtering practices, poor sender reputation, authentication failures, and inadequate list hygiene. AT&T uses distinct filtering methods and may be more aggressive than other ISPs. Solutions involve addressing the outage, improving email authentication (SPF, DKIM, DMARC), monitoring and acting on feedback loops and bounce rates, proper IP warming, maintaining valid rDNS records, practicing good list hygiene, monitoring data quality, and segmenting sending. Data quality and how that data is actioned is very important for keeping engagement metrics up. Correct authentication and reputation management are critical, as blocks often occur despite seemingly correct configurations.

AT&T experienced blocking issues due to a combination of factors, including a major outage, stricter filtering policies, and problems with sender reputation. Some marketers observed widespread blocking affecting various platforms and domains. Contributing factors included poor IP reputation (potentially due to blacklisting), authentication failures (SPF, DKIM, DMARC), and inadequate list hygiene. Resolution involved addressing the outage, improving authentication, monitoring and acting on feedback loops and bounce rates, warming up IP addresses properly, maintaining valid rDNS records, and practicing good list hygiene.

AT&T's email blocking can be attributed to its unique and potentially more aggressive filtering methods compared to other ISPs. Correct authentication (SPF, DKIM, DMARC) and a positive sender reputation are crucial, as blocks often result from failures in these areas, even with seemingly correct configurations. High data quality and good data handling processes are of utmost importance, including how data is actioned based on engagement metrics and cleaning of data.

AT&T blocks emails to protect customers from spam and malicious content using various filtering techniques. Key factors leading to blocking include high complaint rates, blacklisted IPs, and authentication failures. Maintaining a good sender reputation is critical, as AT&T, like other ISPs, uses this as a primary filter. Implementing DMARC helps verify email authenticity. Keeping SPF records up-to-date and respecting user preferences regarding unsubscribing are essential for preventing blocks. Regularly monitoring sending reputation using tools such as Google Postmaster Tools is best practice.