Why are email clients being blocked by AT&T and how was it resolved?
Summary
What email marketers say11Marketer opinions
Marketer from Email Geeks shares they are seeing clients being blocked at ATT on different platforms and it started Friday. Some clients are just some IPs and some are not impacted at all.
Email marketer from GetResponse advises using dedicated IPs, so the senders are not impacted by other people's bad behaviour. They advise using the dedicated IP correctly so the reputation remains high.
Marketer from Email Geeks says they saw this starting on Saturday across multiple domains and their respective sets of dedicated IP addresses, and they've sent an email to the ATT postmaster.
Marketer from Email Geeks says they were seeing this, too, starting Friday, and it resolved earlier this morning (Pacific Time).
Email marketer from Mailjet advises senders to authenticate their emails using SPF, DKIM, and DMARC to improve deliverability to AT&T. They suggest monitoring sender reputation and promptly addressing any issues or blacklistings.
Marketer from Email Geeks mentions that AT&T had a major outage over the weekend, and most of it should be fixed now.
Email marketer from Reddit notes that AT&T has become more strict with their filtering. They recommend closely monitoring bounce rates and feedback loops, as well as segmenting sending to isolate any problem IPs.
Email marketer from DeliverabilityConsultant.com advises that properly warming up new IP addresses is crucial when starting to send emails to AT&T customers. Ramping up sending volume gradually and monitoring engagement can prevent being blocked.
Email marketer from EmailProviderBlog.com recommends practicing good list hygiene. They claim that regularly removing inactive or unengaged subscribers prevents high bounce rates and complaints, leading to improved deliverability with ISPs like AT&T.
Email marketer from EmailGeek Forum suggests checking IP reputation using online tools. They explain that being listed on a major blacklist can lead to AT&T blocking emails and recommend taking steps to remove IPs from blacklists.
Email marketer from Stack Overflow stresses that having a valid reverse DNS (rDNS) record for your sending IP address is important. They claim AT&T, like other ISPs, uses rDNS to verify the legitimacy of the sender.
What the experts say3Expert opinions
Expert from Spam Resource emphasises the importance of correct authentication (SPF, DKIM, DMARC) and maintaining a positive sender reputation with AT&T. Blocks often arise from failing authentication or poor reputation scores, even if technical configurations seem correct.
Expert from Spam Resource explains that different ISPs use different filtering methods, and AT&T might be more aggressive or have unique filtering rules that trigger blocks, even if emails pass through other providers. They recommend carefully reviewing bounce messages and feedback loops specific to AT&T to diagnose the issue.
Expert from Word to the Wise details, that the quality of data you are sending to and how you handle that data is extremely important. So it is important to manage this with engagement metrics, and cleaning of data.
What the documentation says5Technical articles
Documentation from Google Bulk Sender Guidelines specifies that even though it's Google's documentation it's best practise for all ESP's to review. They recommend consistently monitor your sending reputation via Google Postmaster Tools, implement authentication (SPF, DKIM, DMARC), and respect user preferences regarding unsubscribing to prevent low reputation and therefore blocking.
Documentation from RFC Editor explains the importance of keeping SPF records up to date to ensure valid sources are listed. If sending practices change, the SPF records need to reflect this. Failure to do so can result in emails being blocked.
Documentation from DMARC.org says implementing DMARC helps ensure AT&T (and other providers) can verify that emails are genuinely from the stated domain, reducing the chances of emails being flagged as spam. They strongly recommend a DMARC policy of 'reject' or 'quarantine' after thorough testing.
Documentation from SparkPost highlights the importance of sender reputation. They explain that AT&T, like other ISPs, uses sender reputation as a key factor in determining whether to block or filter email. Poor sending practices negatively impact reputation.
Documentation from AT&T Postmaster FAQ explains that AT&T employs various filtering techniques to protect customers from spam and malicious emails. Blocking can occur due to factors like high complaint rates, sending from blacklisted IPs, or authentication issues.